@LeeP - you misread that last part. My plan is to use the original 30A breaker, not the 20A.
@Dads50 - those were responses to the original question which was the reverse of mine. I'm using a 12V switch in a 6V system (but with the original 6V, 30A breaker), and other than being able to dim the instrument panel lights WAY down, I've convinced myself that it'll work fine.
