What it's resting on: There's a pad in the middle of the axle, looks to be wood with probably some old tire sections I think, like up front. There are a few supports/beams/whatever you call them straddling the frame from the axle forward, each with pads in the middle. The beams look like wood but there ARE angle iron supports welded across in places, I'm assuming they're helping support the wood. What's keeping the boat straight up are some cheesy looking but effective pads tied to the rear guide bars, which support the boat at the boat's extreme edges. Plus the guide bars themselves... So then- the entire weight of the boat is being supported by its keel, the strongest part of the boat. And those guide posts are plenty beefy enough to keep the boat from rocking. Nothing to cause any hook that I can see? As to catastrophe, chances are high the worst that would happen is the boat rolls back into the water.
first time we pulled the SkipperLiner out, it was sitting on a single axle narrow-frame trailer with normal 8' wheel spacing; I installed a pair of 4x6 bunks running the length of the trailer, but they're only spaced 33" apart... The boat is 168" wide. The trailer has lateral I-beam supports, but at the time, they weren't bunked to fit the boat; the boat could roll over nearly 6" before any more hull hit the supports- and that's exactly what happened on the hard when the left tires hit a low spot in the asphalt. But the boat righted up fortunately. But what a heart-stopper!
--As to this video, the boat and its pull-out is definitely unorthodox, but I can relate! -- you do what you have to do, and hope for the best I guess