Thanks for the input on this. It looks like in my case the act of trailering forces air into the cab thru the front causing an overpressure in the interior. At 55 the upper door frames were really trying to deflect outward. After the P1K was trailered, wrapped, and our gealer gave us the bad news, my son who is an amazing diagnostic mechanic, commented this thing is giong to overpressure when we tow it. We need to open or crack some side panels.
The bummer is that this unit is our on call transport to do some pretty remote telecom/ repeater HVAC service. That necessitates trailering, usually during the winter when towing with an open panel (s) is the last thing you want to do. Since road spray, snow slush and gravel, coats trailers during the winter, I was contemplating some kind of custom cover/bra deal to anyway. Another science project incoming