You've probably already seen this, but if not, it is a great resource for boondocking. You can zoom in pretty far and see the individual forest roads, in most places. Then, you can download the corresponding Motor Vehicle Use Map from the local ranger districts to see where dispersed camping is permitted.
I use this map from time to time, but it seems to me that they must have recently upgraded their server or something -- the zooming and panning is a lot easier than it was just a few months ago, I think.
Anyway, here's the link:
The map
2012 Fun Finder X-139 "Boondock Style" (axle-flipped and extra insulation)
2013 Toyota Tacoma Off-Road (semi-beefy tires and components)
Our trips -- pix and textAbout our trailer"A journey of a thousand miles begins with a single list."