Now that I thought back on my over crowded 30g, it was the sps corals that had the problem not the fish. So +1 on the keep a good eye on your tank. I guess it could be be fine long term, you just wont have much of a margin of error.
I have a bigger tank now but still no nem. I really love clowns & nems together, I'm working on setting up a tank just for that combo, no power heads & covered over flow so no chance of nem soup.
good luck