I know this post is too late, but oh well. Mapquest says it's just over an hour drive from South Bend to South Haven.
Tuesdays-Thursdays are usually test and tune days from 5:30 to 8:30. $60 gets you on the track for 3-4 sessions of 15-20 minutes.
I had a great time. Spent the first session learning the track, and the other two sessions working on lines and body positioning. In my first session I had a little off track excursion after blowing my braking point coming into T1. There was a shifter kart there and he was absolutly flying, unbelievable! I'd love to take a spin in that kart, what a rush!