Grand Rapids Mi late Sept

Hidden Ridge RV Resort is very nice and is adjacent to US-131 (at exit 59, south of Grand Rapids) for easy access to the Grand Rapids area.
If you didn't want to drive into Grand Rapids to visit ArtPrize you could drive from Hidden Ridge to the Meijer Store on 54th St. (about 19 miles from Hidden Ridge) and then ride The Rapid (name of the Bus Service) from there to downtown Grand Rapids. That would keep you from getting into any inner-city driving.
At the Meijer Store you can purchase an ArtPrize Metro Pass ($5 each) to enjoy unlimited rides on the Silver Line and 10 free rides on all fixed Rapid routes for the duration of ArtPrize.
If you like casinos there is one about 2 miles north of the Hidden Ridge RV Resort.

Grand Rogue is not usually open except by appointment. Nice place, but funny campground as far as when it's open etc.

Dutch Treat in Zeeland would be worth a look. And there's one in Cedar Springs near 131 that my parents used to stay in. They seemed to like it.

There is the Allendale/West Grand Rapids KOA, about 25 miles pretty much straight west of GR. You might be able to drive to Grand Valley State University and then get public transportation to downtown GR so you don't have to worry about parking downtown. I just don't know which lots at GVSU would be considered visitor parking.

Thanks for the replies. I will be checking into the suggestions.

Hidden Ridge on 131 south of Grand Rapids is a possibility

https://www.sunrvresorts.com/Community/HID?3e3ea140

Another
http://www.grandrogue.com/
or
http://www.woodchipcampground.com/
I think if you camp at Woodchip or Hidden Ridge you could drive to Cutlerville area and take the Silver Line (Bus) to downtown.
https://www.ridetherapid.org/

I have not camped at any of these so cannot recommend

We were originally from Grand Rapids and there are not many campground in the immediate vicinity of the city. There are campgrounds on the lakeshore which would be 1/2 hr to 1 hr away in Grand Haven,Holland areas. There is a campground in Coopersville which is 1/2 hr to the west or in Cedar Springs which is north of Grand Rapids. To the south maybe one at Gun Lake or Yankee Springs Recreational area. As far as shuttles, I would think there should be some information regarding that on their website. Can't help with that. Have fun - art prize is fantastic!