False. Corkage is prefectly legal in WI but falsly represented incorrectly by some places. It is legal and a decent place who is serious with themselves will cork a bottle for you. That said, it isn't entirely common. Many places aren't willing to do it, or heard it is "illegal" from someone or another.
$16 is a ridiculous amount to charge for corkage. That is a joke. The only people who bring in bottles (in any decent drinking state like WI) are people who will be eating well and paying a bunch anyway. Plus you can always refuse corkage. If someone brings in a Franzia box, just say "we don't do that here". But if I bring in something special, that you don't carry, and you want to charge $16 to pull the cork, you are getting a ****ty ass tip. That $16 is coming right out of your tip. Sorry man.
Corkage is cool, and savy places will be cool with it. I have never rocked a beer, but it would be interesting to see hwo it was handled. I would call ahead, and just give them a heads up. To me, it likely won't be worth it unless the corkage fee is really small (<$5), but who knows.