It really doesn't bother me having the sump under the tank in the stand. I too don't have a basement and if I felt this was my forever home I'd *probably* put the sump in the room behind my tank which more or less functions as a fish room / storage room. I keep my frag and qt tanks there + another mini display. It would be pretty easy to do but that being said there wouldn't be much to gain other than water volume. My sump is actually my 3rd choice sump. When I moved houses 2 years ago my 180 gallon tank broke in transit, fortunately I kept my old 112 tank which I was actually going to sell but decided to keep. So that is now my main display a foot shorter and 6 inches narrower. Of course that meant the 180 sump would not fit under the tank. I had another sump from my frag system but that was too wide as well. So I went to the 3rd of 3 sumps I brought with me when I moved. It's smaller, I even had to downsize skimmers but you know what it works. I'm only in the sump twice a week changing filter socks and once a week cleaning skimmer. Since my dosing pump is controller via an app I never have to physically touch it.
When I first set all this stuff up I was really upset going with 2nd choice skimmer and 3rd choice sump, but it's working fine. The tank is doing great, there is room under the stand for everything I dose + auto top off container. If this was my dream setup I'd change things, but it's not so this works for the foreseeable future. One thing I will point out is with filter socks being changed twice a week and not really running a fuge (there is a bit of one there but it's really just a refuge I'm not really growing macro) I don't have to clean out the sump more then once or twice a year which is when I do my yearly skimmer cleaning anyway. If everything wasn't under the stand it would be easier to reach but I generally don't have to touch much down there. As much as I'd love to have pvc running all through my walls and elaborate setup at this point I don't really need it at least until I get a massive display tank.