How far are you from Austin? I met a cool dude who was paralyzed from the waist down in an MC accident. He then built himself a hack like yours so he could wheel himself up and ride from the right side!
He later got into a slight accident and a while later was informed by the police that Texas law states the rider must actually be on the bike. so he build another where he wheels himself up, then climbs aboard the bike.
Real cool dude. He hangs out at Lovejoys on 6h street like all the time. Maybe give the place a ring and ask the owner [Eric] if he wouldnt mind giving you his info or taking down your info to hand to him next time he comes in. I'm sure he'd be down to help ya out with your build if need be.
I'll see if I can find some pics of his rig and post back