Your pics illustrate why I'll never powder coat a frame or any other critical part that's exposed to the elements!

That's the Curt/Dalan #13556 / Reese/Uhaul #757235.

Like Tom said, you don't have to remove any cladding. The frame rails are not fully enclosed at the end. You fish the carriage bolts and spacers through the opening. There's just enough room. And yes, the spacers have square holes which prevent the carriage bolts from turning, allowing you to tighten the nuts to 50 ft-lbs. The 12mm bolts get torqued to 62 ft-lbs.

You can find the instructions here:

https://www.hitchsource.com/images/c..._13556_INS.PDF

Hope this helps.