Apparently not 100% of National Forest is freely usable. I learned this lesson painfully not long ago. I planned my overnight campout "carefully"... but there were still things I didn't know, even after reading everything I could find online. Namely: there are "pay to stay" campgrounds. You are not allowed to camp within the perimeter without a temporary permit. And even if you try to simply drive through, you might find gates closed.
Somewhere, people have collected this wisdom, I'm sure. Any pointers?
I keep it really simple. I look for a national forest on Google Maps and drive there, adapting as needed. I'm generally looking for one sign: Welcome to X National Forest, and then I'm woo hoo! Home sweet home.
I don't drive deep into the forest (couple miles max), as cell service drops precipitously the further you are from main roads.
I do follow the signage. I want to sleep without worry, and rangers will not hesitate to wake you up at 3 am to move your car.
When in doubt, visit the website for whatever national forest you're in. Most of the information you need will be right at your fingertips, including important warnings like weather/fire risk.
Most national forests have what's called dispersed camping. Those are areas specifically reserved for camping and are almost completely unimproved, but I often find they're too deep in the forest for my liking. Just because there's a dispersed camping area doesn't mean you can camp only there.
Is national forest? Yes.
Is campsite? Yes, but doesn't even need to be a campsite. Park anywhere that's safe and doesn't obstruct, unless restricted.
Is empty? Yes.
Is unrestricted? Yes.
If restricted, abide? Yes.
Is safe? Yes, mostly. Remember bears and bear etiquette. Remember the zero-worry rule: If you're worried about where you're parked, leave. Don't assuage your worry as paranoia, listen to it and find another spot. Even if you unpack your whole van and setup camp. If you're worried, pack up and go find another spot. Peace of mind, especially if you're alone, is worth the aggravation.
Internet? Two bars. Woo hoo!
Trees/shade? Yes.
Score!
Is mine for now, so don't burn it down.
When I exit, not so much as a toenail do I leave behind.
If campgrounds are what you want, the online reservation system for USGOV campgrounds countrywide is here: recreation.gov. Off season you can snag a campground reservation same day sometimes; not so on-season.
Logging roads in the national forest are usually fair game, unless otherwise restricted.
Those intimidating signs that say “Logging Permit Required” are meant for loggers, so try not to get caught with an industrial chainsaw in your van.
Loggers wake up too damn early. Prepare for (what sounds like) a military invasion at 4 AM when the equipment shows up to turn beautiful, innocent trees into money.
Somewhere, people have collected this wisdom, I'm sure. Any pointers?