How inconvenient was your original partial hatch cover flue holder arrangement for the flue exit? A huge PIA. I only used it for one day. It really was just for testing.
I ask because I'm (perhaps unreasonably) reluctant to make holes in the boat, which this avoids. Cutting a 1" hole is not that big a deal. You do need to seal the edges of the core. The flue does not get that hot in this installation. Of course, that is something you would have to confirm. If it does get hot, there are many insulating details that require some fabrication.
If the flue isn't hot it shouldn't represent a burn hazard to using the hatch, but the flue holder seems to be a fairly awkward obstruction, and I note you dropped it quite quickly. Some people hate cutting holes. Also, some people might only use it a few days each year.
