Help on modification of a bandpass subwoofer box !?

I bought this 12" bandpass box that was supposedly really nice and it is but there is one problem. The lip that holds the plexiglass cover on is partially blocking the way for my subwoofer to get in the box. I messsed up already I bought a 12" kicker CVX and there was no way it fit in my box, with the lip the opening for my sub to get in is a sliver under 11" and the cvx's basket was too big to tilt it in. But to get to the point my question is is there an easy way i could saw the lip for the plexiglass off get my sub in there and once my sub is in there screw the lip back on and seal it with some sealer or apoxy or something ? or will that ruin the box'x sound because its a bandpass it needs that to be sealed, but i dont know anything about making or modifying box's so somebody please help !!!???