Tankplank-ing?

Hey there, Master Fledgling here.

Gangplank is a lot of fun, and I tend to do very well with him, be it support, jungle or top. He is great at poking and farms easily, which is nice for me, a renowned farm-failure. But, I only really understand how to play him oranges-to-the-wall-damage-plank -- How is he supposed to work as a tank?

I understand you build an iceborn gauntlet and a spirit visage, but then what? He seems squishy to me regardless, even with his massive heal. His poke becomes negligible and his ult, while powerful, isn't really a game changers for teamfights (it is very good though.) His lack of hard cc makes me question what to do with him. Run in, buff my team with E, heal up mostly from W, drop my ult and ... what? Is that all? Give me some advice on how to build my core with tank-planking (