I don't know anything about the Milwaukee State Fair RV Park. I did find a web site for the Wisconsin State Fair Park, wasn't sure if that was the same park. The address is http://www.wistatefair.com/home/wsfp/PARK_...IES/rv_park.htm
Fairground RV Parks are a good subject. It is rather hard to find information about them. I keep watching for reviews, but don't see very many. The best information I have found has been the Gypsy Journal Fairground RV Park directory, but it is very incomplete. Lots of parks are not listed including the one you are looking at. The ones that are listed often do not have directions or telephone numbers.
Fairground Parks are a good less expensive alternative to the private parks, but they aren't for all RVers. Most fairgrounds have few amenities and have activities going on which you might not be interested in (some noisey).
We are currently at the Pima County Fairgrounds in Tucson AZ. I will be writing a review on it soon.
When I previewed this, the above address didn't appear correctly. Hope you can make it work.