I know that different sections of the AT have different rules WRT where you may legally camp. I often see this fact referenced, but I don't recall ever seeing a good resource for actually getting this info. Some of these rules I am familiar with (GSMNP, SNP, NF). Others I'm not so sure about. Let's assume that most of the time I will want to camp legally at the end of the hiking day where ever I end up - presumably not at a shelter (i.e. dispersed camping). As the trail goes in and out of dozens/hundreds of different jurisdictions (National Park, State Park, National Forest, State Forest, State Preserve, private land, etc...) how does one typically figure out out the camping rules for where you happen to be at any given time as they are constantly changing?

1. Rules are posted on signs as you pass from one management area to another:
"Private Property -No Camping Allowed" or "Welcome to insert state name here - Camp only at shelters" or "Welcome to the Butthead National Forest - Dispersed Camping Allowed" for example

2. Rules are indicated in one or more of the major guide books (AT Guide, TH Companion, AT Data Book, etc...) which I don't yet own, but when I do, it will tell me all I need to know:
"After you pass Butthead Gap, 3 miles North of Butthead Shelter, you will be entering the Butthead State Game Area where dispersed camping is not allowed, until you cross over into the Butthead National Forest 8 miles later when you cross the Butthead River." for example

3. You look up the rules for each area before your hike and find the boundaries on your map which you carry with you. (I'm guessing this is not used much).

4. Other???

I'm not so much looking for the info, but rather a comprehensive source of information.