The exhaust is a cat back 2.5 inch system with a single muffler mounted just forward of the rear axle. It is only about 8 months old but the muffler (a Lukey I think) is looking a little sus around the seams. It doesnt seem to leak though. I checked and the pipe is clear of the tank / body as well.
I will check the towbar mounts, although I am fairly sure it is all secure - it is a good point.
I think from memory I have noticed it getting hot before but it was some time ago. I only noticed it yesterday when I went to get the jockey wheel from the underfloor compartment.
Guess it could also be a failing diff, although there isnt a direct path for heat transfer.
Admitedly I had given it a fairly hard time, cruising 200km at 100kph+ with an 1100kg ski boat, 2 adults and 3 kids and a bunch of luggage.
Time to by an F truck me thinks.