Good luck with that one I've never heard a definitive answer to trail riding north of the border.

From a legal view it's completely different to England, byways etc don't exist in Scotland, I'm not sure the "offroady" bits of RTA apply either, but can't be certain on this, and the trespass laws are definitely different.

Unless you're causing damage then there's little they can do to stop you other then tell you to booger off, although I've never yet argued with someone holding a shotgun.