I use a 75 gal tank as a sump for about 300 gallons in tanks, I don't use baffles (to me they get in the way of maintenance) and are restrictive to being creative. I use media submerged in bags.
The thing is a sump in itself, is not a filter, its just a box to put filtration media, and equipment you don't want inside in your main show tank.
I hang filter socks on the fluent pipes to the sump, and pack it full of bio media.

I also fill it with lots of other stuff (anything that will grow bio-film)that can be used to jump start cycles on other tanks, and grow out fry in them. There are no rules as to what can do, or where to place them (in another room, on another floor) as long as you obey the law of gravity.

I have used a pond as a sump, and I know an aquarist the puts his sumps in a basement to keep the water on the 1st floor cooler, anything is possible.