Most stands designed for glass tanks support the tank only around the outside edges or plastic trim and the middle is open. I also agree on using a bulkhead to seal it up but I would specify a thread by thread bulkhead and use threaded PVC plugs with either teflon crayon stick sealer or paste on the threads. Take plenty of time preparing the bulkhead and plugs and it will never leak. By time I mean use a small jewelers or nail file or a pocket knife and scrape of file any excess plastic flashing out of the threads left over from the molding process, this one simple step saves a million headaches from slow drips or seepage due to poorly fitting threads. Flashing causes teflon tape to tear or rub out and paste to squeeze out so you do not get a good seal. Also smooth out the molding lines on the flat surfaces where the gasket goes, again to eliminate leaks. Use no sealants or thread gunk on the lock nut, hand tighten and maye 1/4 turn with pliers only, do not over tighten. The gasket always goes on the flange side of the bulkhead regardless if its on the inside or outside, always against the flange and always dry, no sealants let the rubber vulcanize itself to the glass naturally and it will seal better.
In your case, if you are going to have a sand bed or substrate you may try installing the bulkhead from the outside (flange on the dry side) so it does not protrude as far under the tank and cause clearance problems with a stand. It does not matter which direction it is installed from again as long as the gasket is on the flange side. You could plug the inside and the bulkhead would barely stick under the tank, probably less than the plastic trim.
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