I could not attend the original event (dang job), but I have wanted to tackle these caches for a while. I am guessing a few others still need to find these caches. Let's get together and join forces.
Info on the trail: The Fred Meijer Flat River Valley Rail Trail is 22 miles long and connects Lowell to Greenville. Lowell to Belding is 15 miles long, so plan on riding a few miles. The trail surface is coarse railroad ballast with paved segments in Belding and Smyrna. In Greenville, it connects to the Fred Meijer Heartland Trail, and in Lowell, it connects to the Fred Meijer Grand River Valley Trail.
The Lowell Showboat Geo-Art consists of 79 caches shaped like the current Showboat on the Flat River just off M-21. The caches are hidden along the rail trail between Belding and Lowell, which goes through Smyrna and follows the Flat River. Years ago, the Showboat used to head south along the river to its current location to set up for shows.
Caches are along the Fred Meijer Flat River Valley Rail Trail between Belding and Lowell. Parking is in Lowell and Belding. Waypoints for those are listed in 01 Lowell Showboat.