What I did for my trailer was to drill a hole in one side of the tube for each bolt, and a larger hole in the opposite side of each bolt hole, to give enough room for a screwdriver to fit inside to tighten the bolt. That way the bolts tighten on just the wall of the pipe only, instead of going all the way through and crushing the pipe as they're tightened. I think I got the idea from someone else on here.