On the SDW I’ve done similar but in a bivvy bag. Id not be comfortable putting a tent up to be honest but even so that farmer is just needlessly confrontational. It’s obvious the guy wasnt there as part of a group having a noisy booze up. It was 6am, give the guy a ticking off if you feel it necessary and tell him you’ll check he’s gone in half an hour. If you really have to be that way.
The old turn up late, leave early rule usually works. Leave nothing behind either, that goes without saying.
A word from the farmer, an apology from the rider is all that situation needed.
The Sun legal info at the bottom of the page is the really important part. It points out that in Scotland, this likely wouldn’t have been a problem. The real issue is the terrible land access rights we have here in England. That’s the scandal, not the guy doing the lajog.