hey leo, dont know to much about flies but what i would do is just put em in a plastic box with holes and and just let em air dry.i know they use wax to make them float for dry flies not sure it would make a difference though,for salt water.
I always soak my flies & plugs in a SALT-X solution then rinse off with tap water then let dry before returning back to the storage box. Rust is never a problem