Typically those hatches are Lexan or some other plastic material. If removable, I would replace the clear panel and install a Maxx Fan. If not removable, then I would consider prudence if cutting the clear panel itself. Possibly even get a replacement hatch cover.
You want something you can use in the rain and to keep bugs out. What you have now is deficient in those two scenarios, right?
Beastie 3: 2002 7.3 EB Cargo: Agile TTB, CCV Mid Top, Custom Walk Through, Lots of stuff added. BlingMyRig.com