One of the key items I had on my mods list was the installation of a skid plate under the frame at the rear of the trailer. Reading some of the Grand Design forums on-line, some owners have managed to snag the bottom lip of the rear wall on either the ground or an object and actually wound up ripping the entire back wall loose! I didn't want that happening to us especially as we do go off road a bit when down south. One preventative solution is to attach a steel plate between the rear two frame cross members and extend it to just behind the back wall. Hopefully that should provide enough protection so that if the bottom does drag it won't cause any serious damage. Dragos Spring & Welding in Kamloops did the work and by the look of it did a good clean job.
Here is a before picture showing that it would be quite easy to snag the back end.
They also reinforced those little triangular bumpers as well