The line make it hard
"A qualifying cache must have the designation Ice Age Trail in the title or cache page description. "
It is possible if every ok caches has the exact text "Ice Age Trail", IAT in the name/description
I looked at some users list and the first cache i found was
http://coord.info/GCGRAM "Along the Trail" It has not "Ice Age Trail" in the description but refers to som trail and that is it the "Ice Age Trail" is probably only obvious when you look at at map with the trail
That makes it impossible to create a good checker
But it is not that hard to find out manual.
Search for Ice Age Trail and Wisconsin in the wild card search in the pgc dashboard. Do the same for the abbreviations and you will found most caches.
Then is it only to look along the trail in the missing counties and look for more finds. Look in the descripton to se if it is ok