My first time solo camping was at William O'Brien State Park on a Sunday evening. Weekends have been packed and reservations scarce for months at state parks in Minnesota. Arriving on a Sunday afternoon was a dream—very few people in the campground loop (especially the non-electric ones), but still able to take advantage of a weekend day.

Per others' advice, I stayed at Savannah campground because the sites are slightly bigger and more private than Riverway. Compared to Wild River State Park, the sites at Savannah are pretty cramped with inconsistent vegetation between sites. I wouldn't want to stay here when the loop is fully reserved. On a Sunday evening with only one other site reserved, it felt like I had the place to myself.

Site 117 was level, had decent privacy, and was more spacious than some of the other sites (could have put up a 3-5 person tent and a bug house). The fire pit was clean and had a grate on top. There were trees to hang a hammock. The hiking trail was about 500' away, and you could hear the occasional hiker. When the wind died down, you could also occasionally hear the loud motorcycles on the highway. Water was easy to access, but the pit toilet is in the next loop over. If I stayed again, I might try site 121 or 123 since they have more privacy.

Sites 98, 110, 111, 112, 113, and 114 are right on the road into the campground with some tree coverage and prairie behind. These do not feel very private at all.

A couple random notes: 

• Firewood is $6/bundle. Self-pay available at site 74e if the ranger station is closed. Bring exact change since you'll be paying by envelope.
• Cell reception for T-Mobile was minimal to non-existent. Wifi is available in the visitor center parking lot.
• Do yourself a favor and arrive in Marine on St. Croix via Broadway Street / Maple Street. The tree canopy, winding roads, and tunnel are worth it.