I'll say this, if that buggy is secure, he is a Hella lot safer than those nutty TC guys. A 2015 F450 has a payload of 5,500lbs or close. What you see here is just grocery getter springs on the F450. The 2011-2016 has super light springs made for ride quality. We have a friend with a 2013 F250 and with 2 square bales, and 4 bags of feed, long with two horses in a two horse aluminum BP sets the truck on the stops. That isn't more than 1,700lbs.
This guy is probably right at his axle weight
Under his tires, over his Gross Vehicle Weight. By maybe 1,700lbs. I'd say:
Rear axle: 9850lbs
Front axle: 5900lbs
Total truck 15,750lbs....
Under max trailer weight....
Brakes fine...handles acceptable. Let it roll