OK, the next best thing is probably a customized IOS tank.
(1) Figure out what's the maximum tank size you can fit in.
(2) Come up with a list of filtration media & equipment you're planning to have.
(3) Use info in (2) to size up your IOS partition.
You'll have a pretty good idea how your tank will look like after completing step (3).
Draw out your tank specs(with measurement), or make a small model out of cardboard for your tank maker.