so I have processed this more.
and I think to make it work you need to make a number of changes.
Luffy I think needs to lose his powers and instead become more of just straight up punch fighter with super strength and tough skin (aka luke cagish) a cannon ball is coming... he punches it back.
zoro is going to have to lose his third sword.there is absolutely no way to make mouth sword fighting look any good in live action.
usopp would likely need to become a real sniper with a gun instead of slingshot or make him a tech guy.
nami would likely just be eye candy, maybe they would remember she is a thief and use her as a black widow like character.
and sanji of course would be a kick fighter.
I imagine you cut out the boat as well as main story wise not that much actually takes place on the sea. You just have to have them travel from area to area.
at which point even if you keep the original story for the most part and playfulness it still won't be anything close to one piece.
How disconcerting is Usopp's nose going to look in live-action?
they most likely would ditch the nose or just make it a little longer than usual.