LT are a upgrade option on several high end RV trailer brands or lines within a brand, and are preferred on the heavier trailers running interstate highways as the ST is restricted to 65 mph.
Years back we had a good choice of usa made 15" LT tires in C /D and E load ranges due to 1/2 ton trucks requirements. Todays 1/2 ton trucks don't use 15" tires anymore so the usa mfg has dropped them all with exception to a LT235/75-15 C at 19801 lbs capacity and a Goodyear Wrangler HT in a LT215/75-15 D ar 2085 lbs capacity.
Other 15" LT or all position commercial grade tires are;
Maxxis LT U-168 are a commercial grade tire with several 15" sizes and have became popular with all types of trailer owners.
Vanco 2 from Continental another popular tire for trailer users has several 15" sizes and load capacities.
Your OEM tires are 2150 lb load rated so there is no benefit of using a E tire at 2830 lbs at 80 psi as you simply don't have enough axle load. Heavier tires are no benefit when derated with 50-65 psi in them.
Do a google on ST tires vs LT for best education on the subject. This gets you input from all types of trailer websites and not just RV web.
