Gooseberry Falls State Park, MN

Nights of May 22nd, 23rd, and 24th (Memorial Day weekend).

This is a beautiful park, however plan well in advance, booking opened on Feb 1st, and there were 3 or 4 spots left when I booked on Feb 2nd.
No sites with hookups at this campground, so you should have a large battery bank to draw on, a solar system, or a nice inverter generator to recharge with.