Blew out back RH window with my camper tonight,,,, Confused

Or another possibility? Rvs are not precision engineered. The 5er could be manufactured "out of square" giving you that slim 1-1/2" clearance on the left and negative clearance on the right while making a sharp turn.

Why not hitch up and go through the right hand turn sequence while having an assistant watch how sharp you can turn and/or why you hit your cab at a much lessor angle?

Either way, I would not be comfortable with that slim of clearance. I never came across a perfectly level campsite and approach to match.