I am a big fan of the barb/danio+ loach set-ups. A lot of hardy options. I know many are found in a wide range of temperatures, just be mindful that some river fish are not going to take well to 83F. I think the common wisdom for a lot of these species is to keep them under 81 but on the other hand when I look at the area they are from I see the waters often reaching 85F in the summer.
If it was me I would try some golden barbs, kuhli loaches, and dwarf chain loaches. All three are found in a large range of temperatures and in my opinion are beautiful.