I'll be a devil's advocate here - my fishroom has a bank of 20 gallon tanks I use for rearing young fish. They are end out - narrow end facing the eye, and have been set up like that for 25 years (not all are 25 years old though! Most are 10 plus). This is the 3rd room they've been in, but the stand design has been the same - there are overhangs front and back, 3 inches each way. They sat on 2x4 or 2x6 bars, and the actual frame to wood contact was only about 4 inches total. In my new set up, I had some scrap 3/4 plywood 18 inches wide that I screwed into the beams for added support. So those tanks have sat on wood for most of their length for the past few weeks.
I have never had a leak or a tank failure from any of these racks.
They have always been on cement floors though. If they were on wooden floors that moved even slightly from people walking around the room I would support every inch of frame.
I have the same set up for my 10 gallon killie tanks, although they sit on stryrofoam because not all have frames. Again, no seam splits, no shattered glass. no water loss.
Anything above 25 gallons gets full frame support, but every tank I have ever had fail (A too old 75 and 2 33 gallon tanks in the last 40 years of running 15-50 tanks) has been on a traditional stand. The 33s had a manufacturing defect (poor siliconing).
Don't do this at home? If your floor is solid, unbending and not on beams, why not? In a family room, 3/4 plywood may not be as cheap as it was, but it is a useful investment.
