The main frame on this bike is fairly short. I would make a sub frame for the bike. I would start by removing the center stand and making a mount that would go in its place and would move the lower rear mount further aft then the main frame and have the mount come out under the exhaust pipe. I would tie the front lower mount to the engine mount bolts. The upper mounts a frame clamp would work fine. A Velorex or similar sidecar would be a blast on this bike.