I protectakoted the floor in my van but tbh I wouldn't bother again, if the floor is in a good condition its not needed and is a waste of time and money.
You will do better to invest in leak free fittings and buy something to use as a drip tray for brush heads.
If you want to waterproof the bulk head then self adhesive lead flashing tape is good for this, if its a large gap fill with self expanding foam first.
Simon