well, 20k-Cs can still have stupendous Rebounding or so... but if their averages indicate that they aren't that great at rebounding, 1-3-1 isn't the worst choice. Your C needs to be an inside defense beast, though - and the PF should be a serviceable outside defender.
Since the PF does switch sides often, he still has a chance to grab some rebounds - check out my team's match today, where I outrebounded my opponent despite playing 1-3-1. My team might be a special case though, but if you can emulate it, this works.