That is exactly why most people consider seahorses a species only tank fish. The best idea you haven't listed would be to remove the horse to it's own tank, or you could take it back to where you bought it.
Neither of your ideas will probably work in the long run. Clowns are hogs and will eat brine even when full on flake food. You will be over feeding your tank and your water quality will go bad. Even if they don't eat the brine, they make so much commotion that your horse probably won't eat.
Removing your horse to a breeding net will only stress your horse, causing quick death. It probably won't even eat in the net anyway. Horses need to eat a couple of times a day. Are you going to stick your arm in the tank, catch the horse, feed it, wait around until it eats, then release it that often? Won't work long term for either you or the horse.
If you're planning on leaving it there permenantly, I wouldn't. Seahorses need room to move and hunt. You'll be signing a death sentence.
BTW, brine shrimp is not a good staple diet for seahorses. If it is wild caught, it will probably only eat live mysids or ghost shrimp, and no, your tank will not provide enough. If it is captive bred, it should be eating frozen mysis on a daily basis.
I hope you take the welfare of your horse to heart and either move it or the percs to their own tank, or take the horse back to wherever you got it, or look for it a new home. Horses can only go for about 3 days without eating before there is irreversable damage, so a decision needs to be made quickly.
