Ah this option is too late unless you have a store in your area that would sell pro-aide adhesive, but I've read of someone using PAX for painting on designs.
You have to mix it and the acrylic properly or it'll get flaky, though. Also it is literally the most annoying thing to scrub off.
Plus side if you can get it right, PAX isn't going anywhere. Chances are you could sleep with it still on and perfectly in place for your next day of con. It won't rub off on anything or anyone either.