[Scott Douglas]

I would concentrate on strapping the box spring to the bars. Two ratchet straps over the top should do that just fine. Then put the mattress on top and strap it to the box spring. Three straps, front, middle and rear should do that. Then I'd add one more going from the right rear corner bar over the top of both mattress and box spring and around the back then over to the other bar at the left rear. That shouldn't move at all. No need to go to the front bumper or rear for that matter. If I had a spare piece of plywood I wanted moved I'd put it on top of the mattress to sandwich it with the box spring. The mattress is going to be the big 'problem' since it is 'soft' and will compress/move on you as you tighten the straps.