Have you thought about a side car? you could mount battries in the side car and if you wanted power the side cars wheel with a electric motor and use your gas engine on the frame. The sort of best of both in a way and not have to try to balance it. I've been thinking about this for myself for something different and GREEN
. It would be different I could sneek in a bigger 4 stroke engine as well with the right type of cover and muffler.
Just some crazy thinking.