A couple of comments- While the vertical capacity of your suspension system might be up to snuff I question the lateral strength. I see no bracing/struts to help with the side forces that turning will produce. I would experiment with side loading your mock up and see if there's much movement. The other aspect that I wonder about with suspension is how the drive forces will be sent to the wheels. Suspension means that the driven wheels are a moving target. So a chain drive will see tightening and loosening of the chain. Careful drive cog/wheel travel arc pivot (as in a simple single swing arm) address this but with a parallelogram controlled wheel movement wheel travel path changes differently. two wheeled bikes with driven wheel suspension generally have a chain tensioner (a rear der) in the system to take up/play out chain as needed. Andy