I think there was a guy on here that drove both wheels with one motor,
i will find the link, maybe only works on dirt...
ran across this,
using a randal comp truck with floating "free spin'' axle,
http://www.alibaba.com/product-free/106808664/Electric_Skateboard_Motor_and_Axle.html
anyways Papo, I am excited to see that you are working on this,
what wheel is that?
another alternative is using the wheels with the belt cogs that are cheaply available for e-boards.
(or the expensive electrifly, really huge, http://wackyboards.blogspot.com/2009/10/electric-hamboard.html )
I was thinking of going the easy route and using existing e-board trucks and mounting a brushless motor on it....
not sure how much they sell that back truck for...