We take this route each year and know it very well but I am not sure which part of Michigan you are coming from. If your route comes anywhere near Cincinnati on the way to HHI then I can help. If not, I don't want to waste your time. HHI is wonderful, I hope you love it as much as we do.
Edited to add: oops! Saw it is Grand Rapids. I googled it and it has you taking a different route than we take. Sorry I am not too helpful. Enjoy your visit, it's lovely.