How would you delineate or modify target volumes for stage I NSCLC abutting the chest wall in a thin patient for whom the traditional SBRT PTV margin extends to the skin?

Truncate the PTV. Evidence is Keane et al., PMID 33239160.

I am surprised that a PTV margin would extend all the way to the skin surface even for the most peripheral lung lesion. The rib and chest wall diameter for the patient in question must be exceptionally thin (diameter <=5 mm)?