You have my sympathy, just another reason I can't stand multi-map designs - they're a pain in the arse to work with.

I could be wrong but I think you need to use something that allows you to paint across seams directly on the model.  Alternatively, and I don't know if it would work for V4, but Vilters discovered quite a biggie in getting rid of zones and merging them into one.  Maybe visit the thread and ask Tony if it will be possible for V4 because that trick he found is pretty damn neat for getting rid of multiple maps - it'll make your life a lot easier if it works.

Click Here for the thread, but I recommend you ask before you try it, just to be sure.