Perhaps I misread the post. I thought he was talking about a "Max Air" kind of thing on top of the roof. As I read it again, he may very well have been talking about the standard roof vent. The ceiling from inside may very well be OK as long as the roof is not pierced. That's what I was trying to help him avoid.
2012 F150 FX4 Ecoboost, 2016 Surveyor 274BHS
2003 Yamaha FJR1300, Demco Premiere Slider
1969 John Deere 1020, 1940 Ford 9N, 1948 Ford 8N
Jonsered 535, Can of WD-40, Duct Tape
Red Green coffee mugs