Try Action Motor Sports in Idaho Falls, Rexburg Motor Sports in Rexburg, or the rental shops in West Yellowstone. I don't know any of the rental shops in West, but it shouldn't be hard to find out. Good luck, hope you guys have a fun trip.
action has best prices and have accomidations availible for a sweet deal as a whole. I hit them and beaver creek lodge in logan which is expensive been there before and they dont pay fuel anymore probably only did it to ride new machine. next time i will rent another pro. Might be my new machine we'll see what a/c does.