Hm, how about this:
El Monte RV has a fly-drive thing, looks like you can fly into a place and drive off in an RV. Looks like they have locations in Dublin, CA (northern CA) and Bellingham, WA. Give 'em a try, maybe you could do a one-way rental to one of those locations.
There's another huge RV rental place out here that I drive past all of the time, off the 5 freeway, but the name escapes me at the moment. If I think of it, I'll let you know.
Oh, and, I hear ya on the wife-kid thing. My wife has been very good about humoring me (I usually go camping with the kids two or three times a year), but now she's wanting a "real" vacation, where we stay in an actual hotel and stuff. I hadn't thought about an RV, but I may have to start. Would be cheaper than the Orlando trip she's looking at.