Don't know about rafting, but we stayed in Northwestern MI and ended up with kayaks and doing some of the rivers around Empire MI. Camped at Indigo Bluffs. They have an RV campground that is OK and a Class A RV Resort side that is very nice.
When I think rafting, I think whitewater, but none of these rivers are that. They do have a nice pace and are great for day trips. There are about 5 in the area.
Dave and Beth
2015 Cornerstone 45J
Ford F-150 and 2016 Polaris Razor