I noticed I was wearing the inside of one of my OFF-ROAD POPUP tires after around 10K miles.
This all started for me when I made many trips between Gatlinburg TN and Silver Lake MS which took me down I59 in Northern ALA which was very rough going over the lifted concrete slabs every 8-10 feet. My poor POPUP would be coming off the ground no matter what speed you was running. What happened to me was I lost the wheel weights on one side of my POPUP trailer. I also was not happy with my mounted shocks which were mounted almost at a 45 degree angle to my full axle. After welding in a new bracket the shocks now look like this google photo...
After changing tires, getting better shocks, and making sure my wheels stayed balanced thing improved tire wear wise big time.
I know this doesn't address your problem all that much but I did have excessive wear on the inside of one of my tires due to the above listed experience.
My OFF-ROAD POPUP trailer weighs in around 4200lbs when on the road...
I have at least 40K now on the two new OFF-ROAD tires and all still looks good. No bouncing going down the road either.
Roy Ken