Tensile Strength of 4" square RV Bumper I'm building a Class II style hitch for mounting on a 4" square RV Bumper. The RV bumper wall thickness is around .090 thousands. The bumper is welded perpendicular to a couple box frames on 60" centers. I intend to mount the hitch directly to the center of the bumper. My question is simply this, does this 4" box bumper have enough tensile strength to withstand loads up to 3,500 lbs and a tongue weight of up to 350 lbs? I would like to be able to pull my Boat behind the RV. Nothing like going camping without the boat, right? My gut tells me no, but without the necessary knowledge to scientifically compute tensile strength of the box frame, I have no way of proving my theory. Does anyone have a quick and dirty method for determining this? If this setup will not work, what wall thickness would be required to withstand the loading of the boat? Thanks in advance for any assistance provided!