Me silly too
But, I think that hole is where the fuel smell on landing comes in???
So far I have left that hole open but the fuel smell on landing that has been discussed in another thread is probably entering through the openings especially that hole which is nearest the vent opening.
I am still guessing on that one.
I am going to close it with pro seal.
Although I am having too much fun flying right now, I hava a small reversed
NACA like scoop to go over a small hole on the bottom of the tunnel to evacuate air, heat, or fuel vapors if any should develop.
So far, the tunnel is cool and no reason to add anything too it.