For future reference, I ended up "fixing" the issue myself.
The kludge involves three pieces of PVC tubes with foam insulation, duct-taped together to form an equivalent rise to the folded headrest, tucked behind the child seat.
(used three smaller tubes instead of one to provide some stability.)
if need be, I can try to provide a picture of the contraption.
From the 2017 Pacific Owner's manual:
NOTE: If the folding, non-adjustable head restraint interferes
with the installation of the child restraint, the
head restraint may be folded and the child seat installed
in front of it.
I would be extremely
wary of placing anything
between the car seat and vehicle seat not explicitly approved by either the car seat and/or vehicle manufacturers - especially anything that alters the surface contact or seat position and thus could alter the physics of a crash. Chrysler approves of the configuration of the 3rd row headrest to be folded with a car seat installed. If you have any doubts as to the correctness or completeness of your particular installation, I very strongly advise reaching out to the car seat manufacturer's customer support team for guidance - Diono and Britax have both been excellent for us in the past with any questions or concerns we have had. Also, many areas offer free car seat installation inspections with certified installers either through police departments or other (typically) non-profit organizations. Please, do not take correct car seat installations lightly.
2017 Pacifica Touring L Plus w/ Customer Preferred Package 25J - Built 11/2016
Advanced SafetyTec, Tire and Wheel Group, KeySense, 8.4 NAV, Wireless Charging Pad, Hands-Free Sliding Doors and Liftgate, 20-Speaker Harman Kardon Sound Group
2016 Ram 2500 Laramie 6.7L CTD Crew Cab, 4x4, Short Bed
Last edited by tsax6010; 09-27-2017 at 06:26 AM.