a 10G tank is 12" long, so it's actually less space
if you laid your tank on its side, you'd end up with one-and-a-half times the floorspace
I just did that with a tank that was taller than deep (a 29G)
the trick is figuring out how to then close the tank (I'm using a hinged screen top) and how to heat/light it (still tweaking that)
this maneuver can tide you over for a while
btw - here's a link to a great tank sizes conversion chart
Standard Tank Sizes