Protecta kote is not up to the job and you will have to keep giving it extra coats. I have seen a few vans done in it and it just doesn't last.
Have a look at a fibreglass floor, it is what WFP companies used before the speed-liner came along. If it is up to the job for flat roofs on the home, and repairs on boat hulls then it will keep the water off your van floor. It also comes in non slip.
Peter