I'd be worried about the foam being sooked into the engine ??
Tempted by the Maccas route The box is so deep, I can't imagine it filling up enough to be an issue - plus it can always be drained off occasionally I suppose.
Yeah i have the airbox on and off enough at the moment to simply tip out any liquid that may collect in there.
I would have thought it would take a very long time to collect a substantial amount though, surely the only thing that can collect is two stroke oil and water, any petrol would evaporate pretty quickly so wouldn't collect, if your filter is good and well oiled then water shouldn't get through anyway,
Probably not the best idea to plug the holes but i've done it now, i know that no dirt can come in through those holes now