They should just charge more when people try to tap in. "Sorry, family from Denver, it's busy today, it's going to cost you an additional $89 each, plus tax, to get into the park today. Will you be using Visa, MasterCard, or American Express to pay for that?"
OR!!!
Put Mickey's out front holding sandwich boards telling guests how much more it will cost them before entering the tapstiles. Then security can legitimately say to people who complain, "Sorry folks, the mouse out front should have told you".