You could fab up a setup like for bicycles where you remove the front tire and just hook up to a tubular setup for the axle. Put the bike in backwards remove the tire, maybe run a axle substitute from side to side of bed, or till a 2d showes up turn sideways with the wheel cocked to side and bike on diagonal in bed. As to towing with TG down, no dont think so.
Had another thought, if no crossbed tool box maybe the axle substitute could run across top front of bed would pull bike in a couplpe of inches more, but actuall would have same thing if facing to rear with the axle sub over top of tail gate and it would be easier to remove and reattach.
