Provided you seal very well then yes with Low qty mist then yes Ply will be fine. Problem then comes from your Spoil board. Even Low volume Mist still creates mositure which gets into spoil board which isn't sealed. Often MDF is used for spoil board because it's cheap.

Really if your planning on using any wet kind lube often, even with air, then you'll want something that's resonably stable.

Depths are usually a multiple of sheet sizes so 18 or 25mm etc.