If you build a 4'x8' catch basin under the stand, how do you ensure that the catch basin doesn't leak when you finally need it? Glass tanks are almost 100% safe from leaks, but a wood basin, with a liner, or a "waterproof" finish, is far from 100% safe from leaks.
I try to put my tank on hard floors, not carpeted floors, because of the flattening effect on the carpet. Then I quickly mop up any minor spills as they happen. Spills haven't been a problem for me. (Of course that jinxes me, and tomorrow I will find 65 gallons of water on my laminate floor!)