Protect the kofgari areas with wax,{melted then solidified.} then just etch the unprotected areas with a repeated brush wipe, rather than risking dipping.
I don't like Fc myself, I prefer sulphuric,, lemon, vinegar & pineapple mostly, but FC is very popular on this forum.
Only etch when you have uninterrupted time, turn your phone off & don't answer the door!
spiral