Cab clearance lights – pros and cons when carrying a camper.

I would say zero advantages, in reference to safety, because the camper is required to have clearance lights at the upper corners.
No clearance issue with modern factory lights....my 2011 Dodge has at least 3-4" of clearance. If anything they are a disadvantage because they shine on the cabover part and is distracting (if you have a queen bed length cabover).