The E350 we had before out current RV had Left-Hand threads on the Left Rear (the duals) ONLY. What a head case that was.
Our B30 (essentially a 350, one-ton) had LH on both left wheels. Then I put disc brakes on it and that put RH on both fronts, leaving LH on the rear. Got to think some tire jockey was going to wring them off with an air impact. Took it all apart, banged the LH out and pressed RH in.
LH on Driver Side makes sense. Where I see problems with RH all around seems to be on trailers, especially tandems like Fivers. If anything works loose, it'll be the Left.