Corsairs have a window on the bottom of the fuse between the inner flaps. I'm looking for suggestions on how to do this. I'm not going for "exact scale", just "approximately scale". Any ideas?

Here's a picture of where the window is supposed to go. I already cut out the 3/32" sheeting in the bellypan where it is to go. It's dimensions are 2.5" x 2.75". The kit is a 1/8 TF Corsair.

In the picture, the nose is up and the tail is down. The two mounting bolts directly to the left and right of the window, and the inboard ends of the inner flaps are on the edges of the picture. Inside the window you'll see the a stringer running vertically (this must remain), the mounting bolt plate running horizontally, and the TE spar running horizontally. Further inside is the retract air canister. And if the angle is just right (not in this picture), you can see daylight from the canopy. Again, I'm going for approximately scale here.

How do I do this?

Thanks,
Juice