Whether something is the right "level" of embarrassing (or anything else, either) is purely a matter of opinion. What is extreme for one person is yawn-boring for someone else. So if it feels like it's on that line for you and your boyfriend where it's pushing the envelope but not going to far, then you've got it right.
As far as your concern about onlookers, it doesn't seem to me that it will cause much of a stir other than giving the employees something to talk about once you leave.
My only suggestion would be to do this in a store not in your usual neighborhood, because it will be an entirely different experience if you see someone that you know.
Give it a try and see how it goes. Happy playing!