How about, whatever makes your perimeter defense higher? I've never played 1-3-1 because in my head, the formation looks like crap. Also, more important for 3-2 zone are the two under the basket, must be solid rebounders. The RnG is a high tempo tactic, so it should depend on stamina as well - don't play it with low stamina.
One more thing, if your overall handling is weak, you can suck it big time if the opponent answers with full court pressing. I played RnG against a bot team which was at the last moment given to a player, and I missed to see that. I expected MtM defense, but was shocked to lose the game as I had over 30 TOs with the second squad.