Here are some photos of a "Bike RV" that my father took in Northern California a few days ago. Notice in the middle photograph that there are at least three derailleurs! Here's what my father wrote:
Found parked alongside US101 on the way to Eureka. He lives in it, has pedalled it all around the US, has been doing this for years. The vehicle weighs 600 lbs or so. The panel above the seat is just a sun/rain shade, not a solar panel. The mechanical details were nicely done but I think the aerodynamics could be improved. On the other hand it's geared low and likely never goes very fast. Small bike wheel in front, fat rubber-tired go-kart wheel in back. I didn't look to see what kind of brakes. All in all it's pretty amazing that the guy could live in and pedal the thing around. I talked to him a bit, and as you might guess he seemed mildly unhinged.
My question is how does he get the thing started? Getting 600 pounds moving is no small task. And going uphill? He appears to have at least three levels of down-gearing. How does he go fast enough to not fall over? Maybe he has to spin the pedals at 120 RPM to even go anywhere. I also don't think the sun/rain shade could be that effective. To me, if I wanted to protect myself against the elements, I would get some kind of acryllic shell to go over the rider's position. It would also be much more aero.
Maybe I'm just more sane that this guy, but if I were to do this sort of thing, I'd get a bike trailer to load all my stuff behind a normal bike. Then I could ride a normal unhindered bike if I wished, leaving the trailer at the campsite. I'd have to sleep in a tent, but that's okay.