I'll bet it's a pretty stable set up. It appears to be a 3/4 or 1 ton Diesel that would weigh close to 6800#. The boat seems to be 20' long with a 50 hp motor. Probably about 1800#. The loading unit is all hydraulic and must be 1200# and is very well attached to the truck frame. With 80% of the weight being below 7' and a side wind able to blow through and under it, it has to be stable. It's actually a pretty nice compact rig that is within all length and weight limits. With the coach weighing over 50K, towing 10,000#'s with probably 600+hp, the driver of the coach probably doesn't feel it's there
edit: I would change the cover to a custom made one with snaps to prevent any movement. I've tried the type pictured on one of our 24' pontoons and the wind can find a way to tear it apart.
2013 43 QGP Allegro Bus
26' Enclosed trailer for toys