Far simpler to just buy the Terratrike Rover I8 tandem with independent pedaling system, and mount the BBSHD, and be riding in a weekend. But if you REALLY like to 'build' stuff and have the extra time on your hands, then might as well do what you are doing, and have some fun ! My next tandem will have All Terrain wheels, 24", and dual batteries for 30 Amphours at 52 volts, and miles and miles of smiles. Holds 500 lbs so despite its modest looking frame, its a beast. Heck you could replace the rear seat and install a cargo bin, and turn it into one heck of a cargo carrier. i.e. You at 150 lbs, the rear cargo at 350 lbs.