Too funny: I can picture Jethro going over backwards when the broom handle chair support lets go. I also like all the ones where the trailer sits up off the deck to create a living space underneath. The initial stability might feel ok, but a decent wake or getting broadside to a wind will make you wish the deck had a much bigger footprint than the trailer.
There are some interesting ones out there that's for sure...
I'm not sure how you'd build this as anything
but a foamie:

From
this page. There's some interesting stuff but you have to match the captions to the pics yourself.
What I'm looking at doing (at least initially) is more like this - the pontoon boat will be a transport platform for camping gear, fishing gear, and a few crab & prawn traps. There simply aren't too many options for having a clear work deck
and accommodations.

Mine will be bigger and have more reserve buoyancy though('unsinkable'). That way I can leave the boat and hike inland or camp on the beach during a storm instead of being tied to the boat for accommodations. A pontoon boat is NOT the place to wait out a storm !
It looks like he's used PVC post caps (used on the tops of pilings to keep water from pooling) on the pontoons rather than flat pipe caps : clever.