someone here created just that using computer fans. The back of the hatch board contained a box to incorporate the electronics and a pre-filter. Really neat solution.I thought about making a custom companion way hatch with solar vents in it when I'm not in the cabin or the hatch is closed. I also keep a Ryobi fan in the cabin. It works well
Simple cross ventilation should suffice, you need a good in and out: dorade vents are on my "next to try" list.