As of September, 20th, 2017, the following list of repeaters were results of a querry for Eldorado and Placer County using "RepeaterBook". 

The green light icon on the rights side of the image is an indicator if there was a signal available at the time of the search.

My go-to frequency for Loon Lake is 145.805 (KA6GWY), and on the Lake Tahoe side it's 147.240 (NR7A)

For the Spider Lake area there is a 70cm band repeater operating nearby on the 444.9875 frequency.

The following 70cm frequencies are listed here in Eldorado County simply for reference, as they are not the frequencies most commonly used by those on the Rubicon Trail. Most folks are on the 2m band for the west and east entrances, then use the 70cm band in the middle of the trail around Spider Lake.