Sorry for busting in...
The idea is good! But, one should never cut the hive - if one can help it. This hole is what? Almost 1" across? Big enough to let in mice?!
This should have been done, (cut) into inner-cover only! If the hole was double wide it would have been the same size as the big one. Top hole is normally about 3/8" X 3" wide. There are no rules written in stone, for this...
I think that holes in bottom board are a waste?
The problem has been solved by cutting the top entrance!
As it was said: "It will do..."