Yes, I keep the male in with the 3 females... As for the mom's getting preggo again, usually there is a break between at least one female getting preggo, and they all nurse all of the babies. When I have a tub full of 3 week olds, that has a fresh bunch of pinks, I'll foster out the weanlings to a tub of like sized babies. Sounds like alot of work, but it's not really...
I did try condo breeding a while back, used my cement racks for a harem of 1.6, pulling the female just before she burst and putting her in a Vision V-18 tub til the babies where weaned. I built a rack of 70 V-18's just for this. I ended up hating it so much I tore it down and sold the tubs... Too much work. And the numbers weren't really making up the extra time and effort spent in all the cleaning. I essentially doubled my breeding females, but wasn't seeing a double in production numbers, so I canned the whole system and went back to 1.3 per tub...