Personally I would start my best players and not worry so much about the bench. So I would go with Garren, Maupin, Ranck at PG, and Carter, Ranck at SG. Plus I think that Ranck is certainly decent as a DIII SG.
If you are stuck on the idea that you need a stud backup SG, then consider a three guard rotation with Maupin the odd man out: Ranck, Garren, Maupin at PG; Carter, Garren at SG. If you stick the three main guys at getting tired you should be fine in a zone.