Having a few days to look at the pictures, I question the ball hitch on the truck. Those three-ball utility hitches obviously have no drop or rise. I have rarely (really never) personally seen a bumper pull horse trailer that didn’t need a drop hitch on a a full size pickup truck to sit level or just slightly trailer-nose-up.
As the owner of two bulldog coupler trailers, both of mine need 8 inch drop hitches to place the coupler parallel to the ground. I also have one of those three-ball mounts on my tractor that I use to move my trailers around the farm. The bulldog hitch trailers, and my third trailer with a different style coupler do not seat well on the ball if there is much of an angular relationship between trailer coupler and the ball mount.
I usually tow these days with a GMC 2500HD truck, but even my Lexus SUV needs an 8 inch drop hitch for my trailers to sit optimally. Does anyone know what towing vehicle was being used?