Our former 2014 Work & Play 30WRS had Westlakes. I kept them at 75-80 psi and when parked at home, they were always kept in the shade with tire covers. After 1.5 years and probably 8000 miles, they looked almost new.
That being said, I still went with G614s on the new Vengeance. But that was because I did it as part of the deal. If G614s were out of my budget, I'd jump on the Sailuns in a heartbeat.
My Towmax blowout and camper damage from four years ago keeps me from being too confident on any E rated tire on a heavy fifth wheel toy hauler.