2020 320s Boondock Front Ladder Frame Schematics

Anyone have a way to know where the roof front horizontal structural bars are located or how to measure them externally? I understand there’s a condensation method but not sure if that will work with the summer heat in the mid Atlantic right now. Somewhere I read they 6-8” above the front window but that’s too vague for me to be confident in drilling. I’ve seen the Airforce Guy’s videos and see “about” where they are but I am looking for accurate numbers. Thank you.