ericsmith32 wrote:
Not interested in strengthening the bumper any. Would rather have a bumper bend vs the frame...
Your RV is built on a TRUCK chassis. Consider the strength of the truck frame rails, and the strength of the RV's rear bodywork, and ask yourself which is more likely to sustain damage if something hits that glorified gutter downspout of a rear bumper.
You're not going to bend the frame backing into something at 1-2 mph. However, that same 1-2 mph collision will crumple your flimsy aluminum rear bumper, pushing it right into your structurally brittle bodywork. (Unfortunately, spoken from experience.)
After I crumpled my stock aluminum bumper, we had a steel box-beam bumper fabricated (with capped-off ends), painted it black with Rustoleum, and then riveted a decorative aluminum cap over the length of the bumper, bend into an "L" shape to cover the top and rear of the new bumper.
Those stock bumpers are nothing more than a cosmetic place to store your stinky slinky, and perhaps a step. However, they offer next to no protection.