I drive in the woods a lot. Often to the end of dead end roads with no turn around while doing survey on the Forest, my long held record is backing up 1 1/2 miles. I'll shift to 2wd to make the turn around a 6 point turn instead of a 10 point turn. 4WD definitely effects turning radius.
If old school 4wd where I gotta shift in neutral and pause to get to 4 wheel low, I don't know. It would rev the engine hard to go 4 mph in 1st so that might get people to back up. Hopefully, I'll never be in the situation to test what my monkey brain would do.