Fredericksburg Access is a free campground with about 10 primitive sites. Grassy coverage with a mix of gravel or grass pull-ins. Lots of trees but still great stargazing at night. We even saw a few meteors!
We went on a late July weekend and only 1 other small group was there. It had just rained but wasn't too mucky. Drive was safe in our heavy converted camper van. No off road vehicle or AWD needed.
Ground is very level and not super rocky so this is a great site for tents. There are vault toilets but no sinks nor dumpsters, so plan ahead for hygiene and waste. Toilets are on flat ground, handicap accessible, and gender neutral. Likely to be a much tougher trip if you used to full hook-up RV camping/glamping, or require showers, but perfect for primitive camping!
The region:
45m to nearest Walmart or tractor supply, so plan ahead. Food, fire starter logs, and lighter fuel available at Thriftway (about 30 min), firewood and ice at Casey's, and McDonald's all in Linn (all 30m) if you need anything.
About water access:
Sites are all within about a 5 min walk from the boat ramp on the Gasconade. Sign reads "no swimming" but there's a nice gravel bar just downstream from the ramp. If you enter the water, be mindful that boats may pass as you try to cross.
The swim there requires crossing a moderately sized river that is relatively swift. This is fine for people who swim well but not recommended for young children or weak swimmers especially without flotation devices. It is swift enough to carry you downstream of your target even for good swimmers, so plan for this, especially for your swim back upstream (recommend walking upstream past dock then floating back across to dock). It's also deep in the center so you're not going to be able to cross with dry items unless you have a container that is waterproof.
Again, it's a wider and quick river, so we had to help our dog across. Took 5-7 min there and 15 to get back (with dog. Mind the rocky/brush areas just downstream of the dock, saw some snakes.