Wear the disposables and cotton underwear under the rubbers. The underwear should absorb anything that leaks outside the nappy. The rubbers should keep all the fluids contained. However, if you flood, you will still need additional protection. I still keep a cloth bed pad under my bottom sheet. If I should ever leak through to that, it's usually only minor. In any case, it's a whole lot easier to wash and dry the bed pad than a mattress pad. I'm a heavy wetter, and I've not had anything get past this combination. I use Molicare Super Plus diapers, cotton boxer-briefs with the legs folded up on themselves, and plastic pants.