Fly into Las Vegas & rent from there. You have multiple choices of rental outfits in Vegas to choose from but I would seriously consider using services such as RV Share & Outdoorsy if I were in your shoes. A guy I work with has 2 RVs he rents out on the side & it seems like a win-win to me but at the end of the day it's about the money (whomever comes out best in a cost-comparison would likely get my biz).
My bottom line .02: Vegas is in easy RV striking distance of pretty much everything out West & is super easy to fly in to with it being one of the busiest airports in the nation.
