I wanted to share my experience with an aftermarket hitch setup and towing a trailer.
*** Installation ***
It took me a good weekend to install the tow hitch (from EcoHitch) and wiring harness (from StealthHitch) myself.
For the hitch itself, I like EcoHitch better than StealthHitch in terms of design. EcoHitch is also slightly cheaper.
For the wiring, you can get the wiring harness kit from StealthHitch. Since I already have EcoHitch, I called StealthHitch and bought just the wiring and the controller for $200, instead of the full kit which is $300. Shout out to folks in this thread https://bmwi.bimmerpost.com/forums/s….php?t=1969710 for information about the correct wires to tap – saved me hours!!!
The hitch height, measured from ground to the top of the receiver opening, is about 13.625", or 13.125" if car is in sports mode. Note that this is with air suspension and EcoHitch; the StealthHitch receiver might be slightly higher, by 0.25" or so. I used a 4.25" riser to make it level with the trailer I towed.
I didnt find a good place to permanently attach the 7 pin socket to. In a pinch, you could jerry-rig and ziptie it to the hitch receiver. Since I prefer a clean look, I made a small sliding door for the cutout in the underbody panel, and stored the 7 pin socket inside the cutout. The sliding door is usually closed, preventing dirt accumulation and rodents. When towing, I simply open the sliding door, grab the 7 pin socket, connect it to the trailer plug, then put it back and close the door.
*** Towing ***
We rented a TT from Cruise America. Gross weight 3800 lb. It has surge brakes, so you do need wiring for the reverse light.
Towing was completely smooth and effortless. Never felt much sway.
At 55 mph, with a bit of headwind (10-15 mph) and a mild temperature of ~55F, the efficiency was ~1.4 miles/kwh. Driving on coastal mountains at 30-45 mph (California highway 1), it rose to ~1.6 miles/kwh.
I used a universal tow mirror from Amazon which fits nicely on the ix mirror.
P.S. The Cruise America trailer is very basic, with a loud furnace that frequently woke us up at night when it ran. We probably wont rent it again.
*** Charging ***
We only had to charge at DCFC twice, both at ElectrifyAmerica. The first EA site has a pull-through station, which was nice. The other EA site has no pull-through stations and we had to be creative (see picture).
We had overnight L2 charging, once at the 14-50 outlet of a RV campground, and once at a "Rivian waypoint" charger at a state park campground. Both were free (or included in the site fee), which saved us $$ since our free EA charging expired.