<<I believe your engine twists in that direction, putting more strain in the right-hand motor mount than the left-hand one. >>
Actually, the strain/twist in foward gear is on the left mount.
But the right mount rarely outlast the left because of exhaust heat fatique...
The reason the diagnosis of right hand mount is BC he mentioned thumping in Reverse.. that is when the twist/lift force
transfers to the right side...[ and lifts the engine off the mount]