Most of our Travel Trailers (Caravans) in the US don't have ESC.
However, I do have trailer brake control (Tuson) that works in conjunction with the trailer brakes and the Jeep braking system. It plugs into the OBDII port of the Jeep and takes brake information from the Jeep computer system. It works very well.......
Our "Caravan" is just over 20' long and weighs in at 5500lbs loaded. We use the Andersen WDH system and, like all WDH systems, you need to first set it up with the QL system OFF. If installed correctly, the Andersen WDH system is pretty much idiot proof and easy/light to hitch/unhitch!
To pick whatever WDH system, you first need to measure your hitch ball receiver height on your trailer and then the "normal" hitch receiver height on the Jeep. That dictates any 'drop' required on the hitch system you wish to use.
Here's a handy vid on the Andersen system from 'Down Under'
You turn off the QL, measure the unloaded wheel arch height front and rear. You then put your trailer on the hitch ball and adjust the WDH so that you get the equivalent differential on your wheel arch heights.
i.e. If you had, say, 51 inch front and 52 inch rear unloaded, you would want to see, say, 50 inch front and 51 inch rear (1" differential as near as dammit) when your trailer weight was on the ball and the WDH was adjusted. You can then activate your QL suspension. This is the correct way to set up the tow system for your caravan. The Andersen system virtually eliminates porpoising and is very quiet and smooth. I like it a lot.
As the previous poster stated, for the Jeep Sway control to kick in, you would have to get some serious sway from your trailer, which could be due to a badly set up trailer. You should have about 15% of the trailer weight actually on the hitch (tongue weight). A trailer too "rear end heavy" or a badly set-up WDH system (not set up with the QL off) might cause these undulations.
Also, have you also checked your tongue weight as a percentage of your trailer weight with a scale?