well I'll tell ya, I had a couple different old tanks that I bought and set up and about a week later I was cleaning one of the 20 gallons (was a regular 20, not a long) and wiping off the top rim and it just... came off in my hand lol. I figured what the hey? It wasn't supporting anything in the first place, might as well leave it.
I don't know about the long tank if the extra 6" of length will have much of a more adverse effect or not. If you were handy enough you might be able to fashion a brace of your own for the center, as that's the most danger you'll find. The seams aren't likely to run into to much trouble on a tank that small.