My rule, is if your buying new wheels, 4.5 is the minimum.

You mention the RK guys in your post. They do use method wheels, but the boss at RK likes as little backspace as possible.

The reason I say 4.5 backspace is the minimum is because 4.7 will rub with 37s. With 4.5 you can go up to 37s, but 35s dont look bad either.