A similar Sprinter Select caravan I looked up has a tare weight of 3027kg with a cargo weight of 1,267kg. The unladen ball weight is 303kg.
The 2019 Ford Explorer seems to have a maximum towing weight of 2,268kg and a maximum ball weight with a WDH of 227kg.
So the entire rig was overloaded before the groceries went in. Then we have God knows how much weight stored down the rear end of the caravan, probably to stop the bum sagging on the tow.
He was passing a semi doing around 110kph. No wonder the tail wanted to wag the dog.
Keith
It's (supposed to be) a Ford Excursion, not an Explorer, but I think it's a Ford Expedition - so it's a wagon version of a Ford F150, and has a towing limit of upto 9,000lbs (or just under 4,500kg)
Page 28 in here; https://www.ford.com/cmslibs/content/dam/brand_ford/en_us/brand/resources/general/pdf/brochures/17RV&TT_Ford_Expedition_Sep7.pdf
I would say also add in the down hill run, and the cutting as problems, as that can cause all manner of problems with wind.