This morning I decided to spend a few minutes on my own genealogy, and searched for Sidney Tanner in CDNC (California Digital Newspaper Collection). One of the results was well after Sidney Tanner's death, but I looked at it anyway and saw this note.
T. S. Kenderdina, who came to this valley in 1858, was a guest of Sam Rolfe yesterday. Mr. Kenderdina comes all the way from Philadelphia. He is an author, having published two volumes, "The California Tramp," and "California Revisited." He crossed the plains with the party of Captain Sidney Tanner. Arriving here he walked all the way from San Bernardino to San Pedro. (San Bernardino Sun, “Personal," 31 August 1910, 5.)
With that it was the task of but a minute to pull up digitized copies of both of the books. A California Tramp has extensive, very detailed information on Sidney Tanner. Kenderdine only names him twice, but he is a constant and peaceable presence through many adventures. Kenderdine later notes, "throughout the journey [Tanner and the other Mormons] showed remarkable tact, both in their dealings with the Indians and our own men."  Here are a few excerpts.
Our party of twenty made arrangements [to travel from Great Salt Lake City to California] with some Mormon freighters, who were going to Southern California for goods, to convey themselves, provisions and baggage to the Pacific. Their charge was $80 a piece. [Equal to about $2,400 today.] . . .
Our means of conveyance were three four-horse springless wagons, in charge of Sydney Tanner, a veteran Mormon. The other teams were owned by the drivers. We got along pleasantly all through the long and trying journey with these men.
We were to go the southern route, which leads through the lower settlements, and then takes across the Great Sandy Desert via the Santa Fe trail, emerging onto the Pacific at San Pedro, which is eight hundred miles southwest from Salt Lake. [Today's Interstate 15 follows this trail, more or less.] This route is only traveled in the winter season, as it is nearly impassable during the summer on account of the extreme heat. [120–121]
Between the Sevier River and Fillmore Valley, Kenderdine gives a description of the accommodations.
We encamped after night on a cedar-covered bluff overlooking the valley, and as we had plenty of fuel we managed to keep at bay the cold night air which surrounded us, and our well-fed campfires shot out brightly into the surrounding darkness. The cedar boughs spread on the stony ground afforded us excellent couches, and with our feet turned towards the fire, Indian fashion, we rolled up in our blankets, and slept like kings in state; the earth our bed, the star-lit sky our canopy. 
They finally arrive in Beaver, where Sidney's family lived, and spent a couple of days there. "Our abstinence so long from vegetables and dairy products made us keen for them, and they were put on to us at high figures. They also knew our failing for pie, and did a fine trade with us in that circular necessity."  There they attended a testimony meeting.
At night we went to a religious meeting held in the schoolhouse. The congregation was rough, and rudely clad, in homespun, calico and buckskin. I saw here what reminded me of the old-time Puritan worship: bowie knives and revolvers in church. There was no regular minister; the services being carried on by different members giving in their "experience." Their language was rough and ungrammatical, and some of the narrations so comical as to set the audience to laughing. Some grew pathetic, and their hearers cried, and on the whole they enjoyed themselves. One told how, when once afflicted with a plague of grasshoppers, prayers for deliverance were made, when flocks of a peculiar bird, strange to that country, came among them and devoured them all. 
Kenderdine talks at length about the Mountain Meadows Massacre, which happened about a year previous. Sidney Tanner had been traveling in the area of the massacre a couple of days after the tragedy, but it is not clear if he provided any information to Kenderdine about what happened, or if he would have known any details, himself.
The country became more rough and uneven as we advanced. Filling our casks at a little stream which crossed our path, we made a dry camp at nightfall, on the summit of the rim of the Great Basin. As we were now approaching a region infested by dangerous Indians, a council of war was held in the evening, for the purpose of choosing officers, appointing guards and making regulations for the government of our company. Sydney Tanner, an old mountaineer and veteran Mormon, was unanimously elected captain . . . The passengers volunteered to stand camp guard, while the more difficult horse guard was to be performed by the teamsters. A short but comprehensive address was made by the captain in regard to our intercourse with the Indians, so that collisions might be avoided, after which the meeting broke up with three loud cheers for the officers elected. Roughly clad, sunburnt, and "bearded like the pard," we formed quite a picturesque group, as we stood encircling a huge campfire . . . 
It is too bad that Sidney Tanner did not leave any record of his adventures. This book just gives a brief flavor of the longstanding relationship he cultivated with the tribes along his route. (Note that although it is used in the following two anecdotes, "Diggers" is an archaic and now offensive term.)
The head men [Paiutes] knew our conductors well from previous intercourse, and shook hands with them quite ostentatiously; winding up with the everlasting cry of "shetcop," a word which springs as naturally to a Digger's lips as does "backsheesh" to those of their near relative, the Egyptian Arab. Shortly after their arrival in camp they commenced dragging fuel from distant points for our use, for which service they expected liberal pay in food and raiment. Our animals were given in their charge. The Mormons adopted this plan altogether while traveling in these regions, and were rarely troubled with having stock stolen; for the Diggers, through interested motives, were true to their trust. 
At a place called Kingston Springs, the wagon train advanced with great caution. They were right to be cautious: early the next year Salt Lake merchants Thomas S. Williams and Parmenia Jackman were killed outside San Bernardino by one of these warring tribes.
Our reason for starting [just before sunset] was to avoid the Kingston Springs Indians, it being dangerous to halt among them at night. Our Mormons reported them as of large size and differing in appearance from the Diggers generally. They rarely show themselves by day, but watch from behind the desert rocks the movements of travelers, and should they halt at night, steal or kill their stock. The reader can hardly imagine how we dreaded the loss of animals on the waterless stretches of from thirty to sixty miles, and with what anxiety we watched them at night. Their loss almost involved our own lives. But by traveling much after sundown, and by the judicious treatment our conductors pursued toward the Indians, we went through safely. Lack of pasturage was made up with rations of wheat, which for the emergencies of desert travel had been carried from the settlements. This, however, was running short, and our teams were getting thin and weak. The alternations of yielding sand and jolting stones were trying to passengers as well as teams, as much of the way we were obliged to walk.