I can tell you live in NC, Jim. For us on the TN side, the Little Slickrock trail is the easiest way to get in. Drive up Citigo Creek, then Doublecamp Creek, and you're there at Farr Gap.
Even 25 years ago, fishing for those wild browns was tough. I always thought the water clarity of Slickrock was very high, higher than most GSMNP streams, and the browns tended to like the slower eddies. It was best to backpack in, that way you could be on the water in the low light of morning and evenings, and that greatly improved your chances.
I've caught rainbows there, but below the lower falls, and that was 20-25 years ago.