On recent trip I just found some good spots along the road, called the sheriff's department for wherever I happened to be and, after getting an Okay, setup for the night.
I used the Adventure Cycling Association (ACA) maps and also several used city parks. In one town the sheriff's department (SO) also sent someone out to unlock the toilets and showers at the city park I was in (the map said to call the SO before setting up camp). In one city there were three of us, all with ACA maps, camping.
city park, it had restrooms and showers
I ended up paying for two campgrounds, one at a reduced, cycle/tent rate (but a real nice campground). I spent one night in a bunkhouse, and two nights in hotels. That leaves me four nights rough.
A couple of rough sites, both with the okay of the local SO