Make my husband your sub, but instruct me as to what to do to him and instruct him to do things. That way he is submisive to me but you still pull the strings.
The problem with this is with everything going on in the world, if he tried stripping in the store hes liable to have them call the cops thinking hes trying some kind of attack or something to the store, or just for the simple fact of exposing himself in public.
He should definitely go in the store alone without the mistress amnd use the letter idea. And speak sire, etc as you stated, and maybe have him take in an additional 4-8 ribbons, hand them out to different customers/workers. Each worker comes back to the clothing areawith an outfit and the ribbon. he goes and tries all the outfits on in front of them, and each worker/customer places the ribbon down next to the one they think is the best, and hes to purchase the top two outfits.