To respond to all the great comments since I posted a couple weeks ago, I completed my trip while towing with my aftermarket class 3 hitch.
I towed a 2850lb compact car on a 750lb uhaul car dolly through the rocky mountains, plus an estimated van cargo and passenger weight of 600lb. I also probably exceeded the aftermarket tongue weight limit of 149lb (versus 360lb tow pkg limit). So it's safe to say I was maxed out.
That being said, the Pacifica did an excellent job throughout. I never noticed any trailer sway even on bumps, curves, uneven construction work, etc. Ambient temperatures were 45-70 degrees, and the transmission temperature stayed around 150-160 degrees, with the exception of two major ascents, where it briefly peaked at 195 and 203 degrees respectively. Coolant and Oil temps also stayed in the normal range. Most descents were mild enough that coasting + wind/friction negated the need for much braking, though some did require moderate intermittent braking—which I did notice some minor brake fade. (side note, I originally thought the dolly came with surge brakes... and it indeed would have been nice to have).
I was easily able to keep up with traffic if I wanted to (even on ascents), but typically traveled slower than normal and kept a large gap when following. I was impressed with the shifting as well. Other than wanting higher RPMs on some down hill runs to ease braking, it maintained high RPMs on steep ascents even if I let off the gas (eg, infrequent shifting). I know cruise control will downshift on descents to maintain your set speed, but it obviously disengages when you hit the brake pedal. So I didn't use it this trip.
My conclusion is the Pacifica with an aftermarket hitch does very well. As long as ambient temperatures and cross-winds or other sway factors are low, it can tow the same as the OEM tow package. In either case, if you disregard the trailer brake requirement for loads over 2,000lb, you'll put some harsh demands on the brakes.
Last edited by dotbot; 10-30-2017 at 03:38 PM.