This is a good one; if you do take out "one too many" supports and the tank heads for the floor, please make sure you catch it on video; it'll be an instant classic!

Josh has a good idea, but it really does depend on the stand. Know any structural engineers? Here's another thought, which is not the greatest solution but will get your sump out; drain the sump and grab a hammer. The only problem with that is cleaning up the glass and it doesn't solve the problem of getting a bigger sump in there. First, you should measure your stand to get an idea of exactly how big a sump you can get in there; I'd be a little surprised if it's much bigger than 40 gallons or so, not the biggest upgrade. Between that and the headache of getting the old out/new in, maybe this is a good time to consider the bigger tank you've always wanted!