The problems I have seen with ST tires, both on the road, and reading about on forums have been with heavy trailers. Not that it cannot happen with yours, but from what I have seen, much lower chance.
Switching to a D or E rated tire wouldn't hurt.
Balance the tires. The cost is minimal for what could be significant improvement in ride, durability, and safety.
Search this and other RV forums for ST tire recommendations. You will find a ton of discussion. I don't use them anymore, but I have a heavy trailer, so I won't make a recommendation.
2011 Brookstone 354TS
2013 F350 SC 6.7 DRW