Privacy and relaxation are the key words here. Arriving in the evening without a reservation, we found this hotel/campsite on the GPS and gave it a try. It's a stately and serene place on large, green riverside grounds with a pretty view of Wittenberg (though the trees probably block it from the hotel itself). The shy but very polite young concierge gave us one of the four very reasonably priced "bicycle huts" near the river; a basic but clean wooden cabin with comfortable beds, closet, a table and camping chairs, and a little porch out front. The spacious and clean camping bathrooms were just across the road--the only thing lacking for budget travellers is a place to cook. After a horrid night of no sleep in Berlin, this was exactly what we needed. The place was so quiet we were afraid to slam our car doors! Obviously this is what people come here for, as the neighbours were highly reserved and barely said hello.
Bread rolls delivered to our door in the morning were also a big plus, and a chip for the electronic gate allowed us to come and go with the car as we pleased. Because we'd left a window ajar in the oppressive heat (which was making our hut smell like a sauna), an epic thunderstorm tore the locked cabin doors open while we were in town, but this is not the kind of place where you have to worry about your stuff going missing (though obviously you shouldn't leave valuables there).
A couple of km outside of town across the river, so only recommended if you arrive by car or bike. Great value at ~ 40 Euros for a hut in high season.