lensrentals.com is my go-to place for anything I can't afford. The Rokinon/Samyang glass I usually own (not the 24mm as it is almost $750), but I'd hate to pay shipping that almost equals the rental fee. I use them for the $10,000 lenses, as I shoot motorsports now and then, but not enough to take out a mortgage to get the best glass for it.
Renting for hiking trips makes little sense for me, because I am usually out there for a month or more, and at that time only the most expensive lenses are a good deal as a rental. For weekend trips, though, if you live close to these places, I'd be renting any lens over $500 before actually buying it, just to make sure the lens actually is worth the investment.
borrowlenses.com has some followers, too, but I never tried them. Similar prices and selection. It's just that the main tech guy for Lensrentals posts on my photo forum, so I use his outfit.
Also - any moon will mess with the star photos. Even if it's just a sliver, it's way brighter than the stars. You need it to be down, so check moon rise/moon set calendar for your dates. It may require getting up super early.
Here's a full moon night star sky from last year, below Bishop Pass - not much of the night sky visible other than that "super moon" that turned the night into day, at least for my camera
f/4.0 20 seconds ISO 1600 with the 16mm f/3.5 AI fisheye - about 3am in the morningMoonlight over Bishop Creek