Aloop Heavyweight Flywheels

I took the magneto cover off my 1996 yz250 yesterday after noticin water dripping from it. The guy who had it before me had put 6 gaskets on the cover to leave enough space for his 'modified' flywheel. The modified flywheel was actually the stock flywheel with what looks to be the worlds biggest flywheel weight. Ingraved on it is Aloop offroad, Colorado 6/98. So I pulled the cover off and found water in the magneto. Guess those 6 gaskets didn't hold up! who would of guessed. Allright, enough sarcasm, what I want to know is how do I make the cover watertight? I checked, and it seems I really have no choice but to use 6 gaskets thickness cause it just won't fit. Does anyone make half to three quarter inch thick gaskets? I can't take the weight off cause its welded on (though I could probably take it off with my trusty grinder...) but i don't really want to. The weight suits my needs perfectly. But I don't think having water in there is a good thing.

Thanks for your help

SS