There are at least 2-3 members on here that tow Jeeps with their Concords and have zero problems, including up and over the Rockies.
I have a 2016 300DS with the Ford V-10, I have towed my bride's Fusion Hybrid with a dolly. No problems, according to the documentation I have I am rated for 7500# of towing.
Look for posts from BlackJeep22 and jjSpeedwagon. IIRC they both were towing Jeeps with the Concord. BlackJeep22 "upgraded" to a DP, but the information is still here on the forum somewhere.
FWIW I seriously doubt you can overwork the E450 chassis with the V-10. We run pretty close to max GVW and other than a bit heavier on the handling you can't tell it from empty.
Aaron