Just joined your forum as I was looking for boondocking locations in the Sierras. I thought I'd chime in on your discussion. I am a gold miner who has a claim tucked way back in a remote canyon. As far as Pot growers are concerned, you will NOT find them on the main road. Especially near a river or an easily accessible creek. They typically are looking for hillside springs or locations in deep canyons where a casual person WON'T find them. They don't want to be where they will easily be bothered. So if you are boondocking on the side of a road, or down a tributary road, I wouldn't be too concerned. And if they do happen upon your vehicle, most likely someone will knock on your door and suggest you go somewhere else, "for your own good". They really don't want to attract any attention.
As far as miners are concerned, they own mining claims, which means they have the mineral rights to the property that they have under claim. They cannot prevent you from entering their claim. And if you happen upon some miners and they are working their claim, (and you want to pan on their claim), heck, I'd approach them and ask them if you can pan there. If someone asked me, my response would be "if you find anything that isn't "chunky", keep it- if you find some chuncks, then bring them by and we can talk. By the way, I am familiar with the Blue Mule- as it is upstream from my claim.
A nice location to boondock for a few days is Tyler Foote Crossing Rd off highway 49 where it crosses the middle fork of the yuba. Very beautiful location, and I think you are able to mine the creek a little ways upstream from the bridge. A good friend of mine, found quite a bit of gold a few years ago in the gravel on the side of the creek there. I wouldn't recommend towing any sort of trailer or long wheelbase vehicle in there as the road is dirt, rocky, one lane wide, VERY windy and on the side of a 1000' cliff (with no guard rail). If you come upon someone driving the other direction, SOMEONE needs to back up to find a "wide" space to pass (the word "wide" isn't the kind of "wide" most people would even consider as the person finding the "wide" space will most likely be parked at a 45% angle on the side of the hill). Spectacular country, but I'd only consider taking a cabover or smaller in there with very high clearance. No two wheel drive with low clearance or you will be very unhappy what happpens to your vehicle (and the cost to tow out of there is very expensive). Personally, I think that road is one of the most amazing roads in the foothills- as you can point between your toes and see the river 1000 feet below. If you come upon mining claim signs, I'd recommend talking to the miners before you mine on their claim as they get testy when people are stealing gold from them.