Had a previous Savoy 32SKT that came with ST 225R15E Marathons. After 2 blow outs I went to Denmans made in Mexico. At that time they were highly regarded. After 2 failures on one trip I purchased 5 new 225/75R16 E BFGoorich Commercial T/A's. Delivered to a campground 300 miles from homes. Best price I found was Trailertiresand wheels. Delivered mounted, balanced and S.S. valve stems.
The XPS Ribs are excellent tires but are much more than you need on your rig. I currently have 20,000 miles on my BFG's with 2 trips to Arizona, Grand Canyon, another trip to California, Yellowstone and 2 trips to Delaware with many shorter trips in between.
Buy LT tires and save the money and damage caused by ST tires.