Wow..... I am no expert but it seems to me to boil down to:
1) ST vs LT - there are pros and cons to each. Weigh these and decide based on your driving/towing habits.
2) buy the best quality tires you can afford for the most peace of mind regardless of designation.
3) many trailers come from the factory with marginal tires based only on load capacity. Consider your loads and upgrade load capacity as necessary.
4) MAINTAIN, MAINTAIN, MAINTAIN!!! Check pressures EVERY trip. Check temps. At every stop. Never drive over the rated speed for the tire.