If your boot stripe is constantly growing stuff then maybe you need to raise your waterline? Agree that dry antifouling will quickly go just as unsightly as your current stripe - can you keep it clean with a bit of a swim with a brush?
1984 Fast/Nicholson 345 "FastForward"
".. there is much you could do at sea with common sense.. and very little you could do without it.."
Capt G E Ericson (from "The Cruel Sea" by Nicholas Monsarrat)