I ride a lot and understand your passion for bikes. I've often thought about a toy hauler, mostly to carry around the bikes, but they are heavy and expensive. I think you'd be hard pressed to find one with the living space you want, decent garage, and a 3/4 or 1 ton tow vehicle for under $50k. But you wouldn't need a full 12' garage unless you were going to maintain a full bike shop in there (which, admittedly, would be really cool).
I'd think about finding a travel trailer with a separate bedroom or bunk area, where the bunks/bed could be removed and you'd have a nice 6-8 X 8 foot area to convert into a bike garage. My BIL has a similar trailer (rear bedroom w/ bunks) that comes in around 8000 lbs, towable for the right 1/2 ton truck, ie, a max tow/payload F150 Ecoboost.
Good luck!