There is a private camp ground just east of Eagle River called Chain of Lakes campground
We've never camped there, but we did drive through a couple years ago to check it out. We were not impressed. The roads were gravel and dusty. Many of the campsites were seasonal rental where the the site is rented the year round. Being the case, many sites have decks and storage sheds giving us the impression that the place seemed rather trashy. Again that was just our impression.
There are several National Forest Service campgrounds
just east of town. We camped there decades ago when I was a kid. They are rustic, or in other words with outhouses and no plug-ins that I am aware of. I'd have to recommend further research to find out if the sites at any of the camp grounds are suitable for trailers.
FAA A&P mechanic, ex-RV dealer parts dept
Retired B-52 Gunner/Flight Examiner, B-52 Crew Chief
2016 Jayco Eagle HT 29.5 FBDS w/ 15,000 BTU AC, 50 amp service, upgraded counter top, thermal pane windows, elec. stab jacks, outside grill, backup camera and MORryde pin box.
2011 GMC 2500HD DURAMAX/ ALLISON