Hi All, I'm a little late to the thread, but I too have had a hard time finding any definitive info on flat towing a 4xe. I just got back from a 17 day trip towing the Wrangler, so I thought I'd summarize what I learned here.
tl;dr: It tows like any other Wrangler, but needs some adjustment to supplemental braking systems and a source of 12V power while towing.
The Good Part:
1) No special concessions are needed for the hybrid drive train. Once the transfer case is in Neutral, the 4xe will tow exactly like a regular Wrangler.
2) I used the Blue Ox baseplate for a JL Wrangler and the Blue Ox plug and play wiring harness for the tail lights. Everything installed with no modifications and the blind spot/cross traffic alert from the tail light sensors wasn't affected by the harness. Any flat towing baseplates and accessories designed for the JL should work fine.
The "Not bad, but needs to be taken into consideration" Part:
Supplemental braking is a bit touchy. I use a Brake Buddy Digital Classic for my supplemental braking. It's designed for a standard ICE setup that includes a vacuum brake booster. When the Brake Buddy starts up, it pumps the brake pedal 5 times to clear the vacuum reservoir of the brake booster so that it doesn't lock up the wheels when the braking pressure is applied to the brake pedal. The pressure setting I used on my 2018 Sport was 65 PSI. According to the weight/pressure table for the Brake Buddy, I should be using 75 PSI to compensate for the weight of the 4xe.
I set it to 75 PSI and did a test stop from about 15 MPH. I received instant whiplash, the forward ejection of all loose objects in the RV, and the "what did you do?!" glare from my spouse.
It turns out that the 4xe has some sort of electric brake booster that is always active and will always work, even when the engine is off. As far as I can tell, there isn't any way to disable it, so you'll need to compensate by having your supplemental braking system of choice push the brake pedal much more gently and with barely any travel. In my case, I now set my Brake Buddy to 7 PSI (it sometimes drifts as high as 12 PSI) so it barely presses the pedal a quarter of the way when it triggers. This worked well for slowing the Jeep and the coach without locking up the wheels on the Jeep. I'm not sure how you would compensate on a fully mechanical system like a Reddy Brake, or other cable driven system unless you can adjust the amount that the cable pulls on the brake pedal.
A side effect of the electric brake booster is that it consumes power from the 12V battery on the Jeep. (Side note: I'm running the Brake Buddy off of a Jumper battery, not the Jeep battery, so power consumption isn't coming from the Brake Buddy) If I tow for a single day and unhook the Jeep and drive it around a little before the next day of towing, I don't have any issues. If I tow for two days straight without unhooking the Jeep, I see the following errors consistently:
1) The message that the battery is charging and the Aux switches are temporarily disabled - This goes away as soon as you run the vehicle for 20-30 mins and let the 12V battery charge while driving.
2) The message that the Stability Control needs to be serviced and the yellow Stability Control error light comes on - This clears within 5 minutes of driving the vehicle
3) One time I had a check engine light come on as well - This cleared after three successful start - run - stop cycles
It seems that having the 12V battery drain significantly while the Jeep isn't running makes some systems pretty angry. I'd recommend adding a battery tender that feeds off of your 12V line on the trailer plug of your RV. I'll be doing this soon in the hope that it will keep those errors from happening.
Hills
I saw some other posts asking about how the extra weight of the 4xe would affect towing up hills. We did some mountains in Wyoming and Montana. I have a Coachmen Mirada on a Ford F-53 chassis with the Triton V10. Probably one of the the most common Class A platforms out there. On a 7% grade, I was able to maintain 45 MPH climbing the mountain. I'd probably consider that the steepest you'd want to climb with the gas V10. Due to an oversight of navigation, we ended up climbing a 10% grade one time. I barely kept it at 18 MPH. I don't recommend trying that. Downhill isn't a problem with the V10's hyperactive downshifting in Tow/Haul mode. On a 7% grade, the engine braking alone did a good job of maintaining speed. On the 10% grade, I had to do a lot of braking (and consequently used the Jeep's supplemental braking a lot as well).
I hope this info is helpful for anyone still looking for answers about flat towiing the 4xe.