If it were mine, I would install a friction drive motor to the front wheel. Several manufactures make the complete kit. Do a search for " Bicycle motors", then find a dealer which sells a friction drive for front wheel. " Staton" is one I know of. I would opt for one with a clutch as well, where engine would be running while sitting still. I have an old Orline/Ohllson & Rice that runs on my front wheel & can easily adapt to 3 wheeler as well.