I mounted an antenna on my 3rd gen with an NMO hood lip mount on the passenger side, on the back of the hood nearest the windshield; not the side. Went with a Midland 6 dB Gain Antenna.
Excellent advice.
Have you had any experience with this "lip mount" from Midland?
https://www.amazon.com/Midland-MXTA27-Universal-Connector-MicroMobile/dp/B0842BB2R9
I haven't seen a Pacifica "in person", and I am wondering if this could be clamped onto one side of the gap where the lift gate opens (at the top, between the faux airfoil and the roof).