If ya want low maintnance with that footprint look into polypterus. Lotsa people keep them in an empty tank except substrate. They do not like bright light. They are a low bio load fish. they do prefer upper 70's to low 80's for temp tho.
Hello. I also had a reef then swithched to freshwater for the same reasons you mentioned. Still wanting the bright colors like the saltwater fish, I decided to go with Africans as well. I went with Malawi haps. I chose this for two reasons. One, the colors of the fish and two, the size of some of the larger haps. I have a 360 (8'x3'x2') and wanted big, bright, active fish. Lots of growing to go, but you get the idea...