Have you heard of Turo.com? It's a website where people rent out their personal vehicles and the prices are generally much less than car rental agencies. Might be a way to save several hundred $.Yeah, it's a big jump but I've read that lodging pricing in general is up. I guess they're trying to make up for lost revenue from 2020 and 2021.
The combined cost of 3 nights in Midvale, 4 nights at GMD and a $1,100 SUV rental is still less than the cost of staying at GMD the whole time and using the Alta Shuttle.
EDIT: I was really surprised with the SUV rental cost. Usually when I reserve one this far out the price is around $600 all-in. I guess they're not letting that happen anymore.