Trailer dimensions were measured to the hull at the centerline of each support.
Looking at your pictures, I would be concerned how the center beams were notched to lower the height of where the keel sits.
Take a look at the pictures of my trailer. Those center supports are not notched.
granted, the load should be carried on the pads as well as the keel, but still - not sure about the notches and the reduced strength in that critical area.
6 support pads vs 8 on my trailer, probably OK for short haul. Years ago in winter, my boat used to sit on 6 jack stands + the keel. But back to your trailer, I would have concern about the notched cross beams
