There is this, too, the Tailgaterz Hang-n-Haul organizer:
I have one, but never used it, going instead for a different way of storing stuff. You can hang it up while in camp, then remove and roll it up with stuff still in it, if you want, to store for next trip.
I might dig it out for this next big trip and use it on one of the van doors or something to see how I like it. They were unavailable on Amazon last I saw. Must be around somewhere, though.
This, too, the Misslo Hanging Shower Organizer ($9 on Amazon):
Have one of those, too, and have used this one, though more inside a closet. Well worth nine bucks to see if it suits your purpose.
Lastly, there are Pelican lid organizers of various sizes that might work:
Hope you find something perfect for your needs!