Why buy a port? You could find a Grommit in the van floor and run a length of hose down and out to the back of your van just zip tie it to the chassis or whatever, stick a Hozelock with endstop on the end. Cheap as chips. I've gone through the floor under my reel so i can lock the van with the reel inside. Any holes can be plugged when you want to sell the van on or covered with ply flooring.