If I'm really concerned about being 'caught', I put the bed down but sleep on my thermarest on the floor with my head under the bed, a sheet hanging over the edge of the bed as a curtain, and various bags arranged around me. 'They' shine their lights in, see the empty bed and move on.
In moderate areas, I hang towels and shirts (and the bag trick) to only conceal my torso and head. I've found that it works a lot better than curtained windows in avoiding suspicion.
You know how every town seems to have an overgrown lot by the highway with cars for sale in it? I carry "For Sale" signs with me and join the crowd for a peaceful night's sleep.
PS I didn't find a good spot in Rhinelander, WI last July. The cop who found me actually pulled his gun on me. I guess I was too close to the Rainbow Gathering...
For California (I'm also a Northern Californian like Catherine) I have found that the first thing to do is to pick up an annual fire permit from the state dept of forestry. This allows campfires, and also outdoor cooking when desired.
Next, keep an eye out for the burn information signs. generally the state and federal lands where roadside or non-developed camping is popular, they will post warnings about need for a burn permit, and also if "all fires" have been suspended. I find this is the easist, most comfortable way to find roadside camping, without having to be concerned about the stealth factor, mid night wakeups from rangers, or other unwanted visitors.
Whenever I visit Yosemite on a whim, and cannot get a site within the park, I just drive north of the 120 boundary. you will quite often fnd tent campers along the south fork of the tolumne river, where they just park on 120 and hike in a few hundred feet. A quarter mile north is Evergreen road which leads to Hetch Hetchy. Anywheres along this road is fine, and there are a number of fire roads to get you away from the traffic. My last night spent out there, I was heading out in the morning and saw another westy that had pulled off along the oadside to the edge of a meadow that is always gorguos with morning fog, deer and a perfect spot for the sunrise. Made a mental note to head for that spot next time.
Also, along hwy 70 through the feather river canyon are many spots for legal roadside camping. there's plenty of services along the route, and if you so dare, you can visit the developed camps close by for the facilities.