I'd second the suggestion that you get a Surtrack half shaft spare..
..rather than a used Trooper one.

The fit on the Surtrack races/Cv is OEM standard......
..... and given you are not going to be pounding the Pearl ( )..
.. should be plenty strong enough for you.

As for the hitch..not sure how a home made 'hidden hitch' variant will help back end protection..
...plus that will presumably involve cutting cladding.

Cheers

Jo