I hadn’t been looking lately; I took a look at one of the local ebike dealers in the Seattle area.
http://www.electricbikeseattle.com/collections/e-bikes
I am shocked by the prices. I am certain you could do it yourself, but if you live somewhere in the Northwest I would be glad to give you a hand installing a hub motor kit on a normal bicycle. It probably would save you a lot of expense.
I used the gas powered bike on local roads, but I knew that if the police saw me it would be a large ticket. They most likely never would have noticed the bike with the electric motor even if I had been traveling at a quick pace on the flat.
We also had a solar panel on our trailer which helped keep the two golf cart deep cycle batteries on it charged. It made more sense than on the camper van. The people here who probably have the most experience with alternative power and living off the grid are probably people who are RV’ers.
My interest is still in manufacturing faired trikes on a small scale with electric motor assist. Checking component prices and seeing the prices being charged for normal ebikes makes me feel more confident that this might actually be getting closer to being feasible.
I am afraid that I am far out of range for an assist on installation.
The best selling ebike in the US is Sondors - which delivers a nice 36v option for $500 (plus $193 shipping). That price point has been a winner so far. gosondors.com
E-bikes are very quiet, and you are visibly pedaling, so they fly under the radar pretty easy.
Good luck on your projects. Better stuff is coming out every year.