My 53 Liner's toilet, shower and bath sink dumped directly to the ground. It was retrofitted with a tank in the late 60s. The water tank was at the front of the trailer with an inlet front curbside.
I recently saw a 53 Flying Cloud with a name sticker exactly the same stylistically as yours. My understanding is the stickers were not applied to all trailers...so yours is pretty cool...hopefully you can preserve it.