sorry gubar - i'm afraid i don't really have much experience (actually no experience) with altering mr's memory limit, adjusting BSP or setting polys to single sided. sorry.
i might be wrong, but to be honest, it sounds like you are over thinking this a little bit. did you try optimizing your scene, deleting your history or going through the objects one by one to see if you can render without them? i would definitely do that. i was having trouble rendering my fly model and DJBLAZER suggested i do that and it really helped me find the problem.
post up a picture of what you're trying to render and maybe that will help us figure out what's going on.