Were you on the Mn. side?
If you look at the Wi-dnr website it says you do not need anything.
Do I need a name and address on my ice fishing shanty or shelter, even if it is portable?
It depends. The name and address (in English) of the person owning or using any fishing shelter must be legibly painted or permanently affixed on the outside of the shelter in block lettering at least one inch square in contrasting colors, when the shelter is left on the ice and is not occupied or otherwise in use.
However, beginning April 1, 2002, fishing shelters that are occupied or otherwise in use and removed from the ice daily are exempt from this requirement. If you remove the shelter from the ice when you come off the ice, a name and address is not required.(copied from the wi-dnr web-site).
Scott