Aaahhh.... I get you. This isn't necessarily camping with permission, no? More like subtle guerilla wild camping.
I'm sadly too wussy for that - plenty of places I 'could' think of then, but none I'd want to enter without that all important permission to be there. Blame my boringly rigid upbringing, but I'd hate to be responsible for spoiling access for others by doing something that has potential to really PO the locals (and I'm not necessarily suggesting that you are, but it does have to be said).
This is just an example, but unfortunately the last pair of machete clutching middle aged, supposedly adult male cammo clad* numpties (I can't being myself to call them fellow bushcrafters although I'm sure they both believed that they were) who entered one of our local woods did not leave it in a good state, digging large holes, hacking at young trees and setting fires all around the area they were camping in. So my opinion is great, if you can be discreet, will treat the land and its resources well, and then leave no trace you were ever there afterwards, why not. After all, if you're that good I'll never even notice.
*It's a description based on actual experience, of course I know that not ALL middle aged cammo clad males are numpties - just these two.