Brown trout are bit more tolerant or warmer lower DO waters, but not much. If you stay with trout, you're still gonna have to put the time and money into maintenance. With brook trout, you're going to need even better water quality. Sounds like you have a rare gem though, mixing in different trout species can add to the fun...
Brook, brown, rainbow, golden rainbow and tiger trout are all good options. That's 5 different fish to catch. As the brown and tiger trout get larger, they'll feed more heavily on your stunted perch/sunfish than did the rainbows, but don't expect them to control their numbers and reduce stunting.
