This is what I do now.
Immediately put the fish into a 30 minute H2O2 bath for 30 minutes, or 45 minute formalin. This knocks off the parasite and seems less traumatic than FW dips.
Then I do tank transfers every other day using copper every time for the remainder of the treatment period. My copper solution uses exactly 60 drops to get to therapeutic copper so I prep the new container, test it, then transfer in. It uses up a lot of copper but it avoids some of the other issues that come along with keeping the fish in the same filthy water for 2-4 weeks (bad bacteria, ammonia, etc.). No filters, just heaters and air stones.