Won't work. It is not the buyer you need to worry about but the buyers
survivors. One can sign away their own rights but not the rights for
another and nothing you can do will protect you 100% from the buyers
survivors. What some home builders do if they are the builder of record
is part the plane and make sure the parts go to different buyers and that
none of them include the airworthyness certificate or registration.
So if you build a homebuilt you cant sell it. There should be some changes
made in these laws.