Get the tube on your back and head for the hills, man! As long as you're behaving in a safety conscious and responsible way, what harm are you doing? Tell someone where you're going, what you're up to and when you expect to be back. Wear an FD. On the (extraordinarily) rare occasions I've encountered Ranger danger; twice the blokes have just wanted to have a look at the tube and a have chuckle at me, and once there was clearly a problem with my presence, but I just couldn't seem to get the tube near enough to the bank to hear what heinous charges were being levelled against me, and since the Ranger danger took its red faced-huffing away back down the hill in its 4x4 after half an hour, I can only conclude that it wasn't
that big a deal, whatever it was
Tubing
rules, and that cliche about the fishing being better where you're not supposed to go, is true

I say go for it!