Hole through floor, connector in/on/under bumper..... Port through side of van.....
Don't bother, too much hassle coupling/uncoupling hoses and connectors, loosing water, reel in and out of van.
Just connect a length of microbore between pump and hosereel and if you include a quick release mounting for the hosereel in the van, then you can use the reel in or out the van and still shut and lock the doors with the microbore through the rubber seals, been using it this way for ages now and works a treat.