I use to do this when I had a smaller van.
get downpipe with end caps, one end gets glued on and the other is theaded.
with the threaded end you cut a groove a few inches long ( just enough for the goose neck to slide through and clear the end of the pipe and screw the cap on)
cut the hose about half a meter longer than the pole when closed and use a hose joiner or quick release.
simon
