Hi Mission.
Dad actually had the Moke dipped in molten metal. Many years ago, after convincing Furphy's that he wasn't insane, the moke was lowered face first into the pot to the halfway point, taken out, turned around and put in again. It came out very wonky but slowly straightened out as it cooled.
Dad had to strengthen many parts of the moke and drill extra holes to allow the gal to drip out, otherwise it could have cooled improperly or exploded as the molten metal tried to escape. You can see from this old photo where there is extra square tube down the sides & a new support behind where the seats should be. If he did it again, he says he would support the area around the front grill and the back of the rear wheel arches too.
The regular post 1980 moke had bodies built from galvanised metal panels, as opposed to being completely dipped after the fact. I'm not sure how they were galvanised, but the coating is far thinner than the industrial coating that ours was covered in. Quite possibly was the zinc paint you speak of.
As for how it's held up - remarkably well. No rust to speak of - the rust that can be seen on the above picture was from other items sitting on the moke as it sat in the yard for years. It comes off easily with some scotch brite or steel wool. There are some minor warps in panels and blobs of leftover gal. By no means a perfectly straight & smooth body like it started out as. The bonnet has some little gal tabs on the inside and hits on the driver's side first when you put it down, so it's not perfectly straight. You can just make out on the photo above the fuel tank compartment how the forward hole is pushed slightly up.
The subframes were galvanised too, and have not warped but do have extra 'filling' in the corners. By no means a perfect finish but very durable, and that was the goal.
So yes - warped a little bit on the long straight panels like the bonnet or inside the side boxes, but still sits straight on the road & you wouldn't notice it unless you were up close & looking for it.