If cost and any other issues aside, I would try for 4, yes. But I recognize that when reality kicks in sometimes we have to tailor our expectations, but it doesn't hurt to explore the possibilities in the meantime. Like maybe you could try for 4', then if you found out that was a no-go, but then if maybe you could find out that 3.5' was workable.. why not. 6" is 6" and the more depth you have the more 'scaping possibilities you get.
I'm sort of with you on the 24" length. I like the look of 30" tall tanks but it's a pain to reach in. With my 280 I already have a problem and I even built a catwalk to help in the matter. Oh, the sacrifices we make..
I guess I can live with wet armpit shirts.
You can always make the stand a little higher if the tank seems shallow at 24".