I think the only reason the touring ones probelm is positioning ie anything from the rear tyre get flung at it which when off roading is alot of rocks, mud, wet etc. which probably causes the cracks. I thin piece of aluminium could solve that problem
also the more weigh on the number plate hanger the more it should be reinforced as it wasnt designed to carry that weigh so maybe some form of an inner steel bar to transfer weight to the rear subframe.
Im only guessing really but most of it makes common sense!!! Does it???