Back to the OP:

Aha, another example of a situation where 4x4 gets people *into* trouble instead of out of it. This is becoming a common theme.

Local advice is useful, and indeed sometimes indispensable. It can lead you to amazing stuff you would never find otherwise. But it's never complete or thoroughly considered. You need to do your homework and fill in the gaps with experience and uncommon sense.

When taking back roads, there is no substitute for a well-tuned "situational B.S." detector. If you start down the local shortcut and your spidey sense starts tingling, you better listen to it ... and back off from the natural tendency to keep pushing on. Stop, get out of the vehicle for a minute and look around, have a cup of tea, look at the map again, and make a decision.