ST tires are rated for 65 mph max, at least all that I'm aware of. LT tires are usually rated higher. However, your fuel mileage will probably drop very quickly the further over 65 you drive.
I've heard/read of lots of people who go to LT tires on fivers and on bigger, heavier trailers it might make some sense but for trailers the size of yours & mine, I think a good ST tire is sufficient. I'd stay away from the Chinese tires, like Towmax, Carlisle, and others, tho. It's important to keep them properly inflated and to not exceed the weight rating. But then, that's true for any tire.
Anyway, that's my opinion. You'll run into others who say all ST tires are junk, and all LT's are great. You just gotta do your research and make your decision based on that.
2008 Ford F250 Super Duty, Lariat, 6.4l PSD, Super Cab. Long Bed
2006 Jayco Jay Flight 27.5 RLS Fifth Wheel