I have that to do also. I'm thinking i will leave it open in the summer, but board it up in the winter . A few more pieces of trim & some clean up. I think it will work!!!
They are in the front & back in the roof overhang. instead of covered soffit, it is covered with chicken wire so nothing can get in. in the winter I will install a 1X10 board in front & back to close it up.