I had the exact same problem on my previous 5th wheel. We did get it fixed at a local fiberglass shop that did custom fiberglass work.
They fixed the damage (we had a seam run down the side) put on a new awning caulked the entire unit state inspection adjusted the brakes packed the wheel bearings and a host of other little things for $3200.
I was happy with the work but we went out for a drive just to look at a new 5th wheel and..... well it is sitting in my driveway now.
I think your plan of the smooth aluminum is a very good one since you have the knowledge and probably the tools to do it. Should look very good when done.
Dave
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