There are times where it is necessary or a good idea to have a washing line (surfing, CLs etc).
I use this on odd occasions.
Take an old windbreak pole (solid not the ones that break in sections) 4 ft is about right and carve a 1" V in the top.
Take some washing line appx 15-20ft long and tie each end to a rear grab handle, round turn and two half hitches is good for this.
Pull out the loop and cross it over in your hands and pull your hands out until they are at max stretch (sort of triangulated figure of 8), appx 1 ft back from this cross bang in 2 awning pegs about 3ft apart and put the line around them.
Take the pole, put the "X" of the cable in the "V" of the pole and lift pole until the line is taughtish, give the pole a light tap to make sure the bottom does not lift out, you can get some extra security to stop the line slipping by looping the line back around the pole once.
You may have to play with the distances as I am doing this from memory.
This gives you a very cheap, light and easy to erect emergency washing line that is hidden behind the van.