Latex Rubber Mold Making

So I'm trying to learn how to make molds of my big-headed men sculptures and it's REALLY time-consuming. Given the fact that my faces have lots of curves and more than a few undercuts, I decided to go the latex rubber in a mother mold route. I got a couple of books and read up on it, but some things are left unsaid. These are the situations where it would be cool to take a class or know somebody else that has done it so I could get some advice. I'm wondering, once I finish putting on the rubber (about an 1/8 of a inch thick, which is approximately 20 coats of rubber, the first ten being 100% rubber and the next ten a 2:1 ratio of rubber to paste maker)--but, I digress--so, as I said, I'm wondering if I've still got some undercuts after the rubber application, am I able to make my mother mold out of plaster at this point? Won't I become interlocked? I think I need to have no undercuts at all to be able to do this. Is there some sort of filler I can use to remove the undercuts? Woe is me...I need to do more research. I'm now into my third or fourth week on this stupid project. I'm starting to wonder if it's worth it.