Buying out of state TT, keeping it in current location.

I live in Illinois and am going to be buying a used RV camper trailer from a private seller in Wisconsin. The camper is located on a lot in a resort and will not be moved. I'm just trying to figure out registration and taxes before making my purchase.

1) Do I register it in Illinois and pay Illinois taxes because that's where we live?

2) Or can I register it in Wisconsin and pay Wisconsin taxes because that's where the camper will be located? 

I have a few weeks before I can look at the camper. So, I want to figure this out in advance.