Crazy idea

I could see a way or two to do it, but it would become more and more difficult as the amount of travel went up. If you limit the travel, you make the ride as stiff as a board, but it would become easier. Too little travel and you will have created a go cart. Another possibility would be to use T-bars in conjunction with a light single tapered leaf spring, which could help in alignment and be a backup for a snapped T-bar. I would probably put the bars at 90 degrees to the axles. One of the problems I foresee, but haven't pondered thru is how to limit the twist of the axle which could be problematic.