OK if I start a thread to describe my efforts to build a stand?
I'm using fir 2X4's for the frame and I'll cover it with other material to make it look a little more like furniture.
To try to get the best fit between the base of the tank and the top frame, I inverted the tank and fitted the lumber directly on the base, checking for daylight between the two.
I found that I had to use the middle sections of the 8 foot boards to get the best flatness. None of the 6 boards I brought home fit perfectly, even though I picked out "straight" ones. Which brings up a question...since I'm not using a plywood top, how important is it to get a perfectly flat surface? Mine isn't perfect in that I could get a piece of paper in between in some areas, though not necessarily at the corners. Without access to a planer/joiner or a belt sander, I can't see any way that normal construction grade lumber will not have some daylight showing over a 4 foot span.
This project gave me a good excuse to start making things using pocket hole joinery. These are done with the Kreg HD jig.