Here is my homemade windscoop in place. I made it from an old parachute I bought from the Army Surplus shop for less than £10 a few years ago, some vinyl PVC for the edges and two sticks for a bit of shaping.

Unfortunately our forward hatch opens backwards, which may be the safest way but means it blocks some of our wind catching potential. I'm hoping that whatever breeze there is will hit the open hatch, be forced upwards and then caught by the windscoop and directed below.

We tried it in place on a very calm day and it did manage to bring some air movement down below and set a plastic bag fluttering so it seems the hatch opening the way it does isn't too much of a hindrance. We'll only know properly when we have a bit more breeze to try it with.