Downsizing help me decide

[gregzz4]

I also don't like a 12" wide tank

I see you want to downsize, but you mentioned 48", and also 21" tall
A 75g is 48x18x21
I like the height for reaching all around the inside

Or you could get something custom made;
48x18x16 is a 60g
Nice width and an easy to work with height. Plus your 4 bulb would probably be enough with a shallow tank