the main thing to look at for LT tires besides the load rating and being able to fit the tires within the wheel well of the RV is the tread pattern - you want as much as possible to have a RIB pattern for lower rolling resistance.
Plenty of good choices out there - the top two are the Michelin XPS Rib and the Bridgestone Duravis R250 but also look at the Toyo H/T, BFG Commercial T/A AS, Cooper Discoverer H/T, Firestone TransForce H/T, Bridgestone Duravis R500 and Michelin LTX M/S2 as possible choices depending on what you can buy locally for a good price.