Thanks--is there a detail or angle I could add that might be able to confirm that?

A close-up view of the tip of the abdomen is often the best way to determine genus (and perhaps species). A dorsal view of the terminalia is probably best for males, and a ventral view of the last few abdominal segments is best for females. If a species is very distinctive in appearance/markings or if someone is very familiar with that species, a determination can sometimes be made without such details. However, many Acroneuria are very similar in appearance. You have a remarkable wealth of Acroneuria species (and other similar perlids) in Tennessee.