Thru-Wall exhaust on window header?
I am trying to add a thru-wall fan in my 1st floor bathroom. The bathroom is 59 inches wall to wall. There is a window of 41 inches. I want to add the fan above the window, but i found a window header on the top. Either side of the header cannot be used as the maximum radius that can be drilled is less than 6 inches. My fan needs a 6 3/8th of hole and further the upper cover is 8 inches. Can i drill a hole on the window load bearing header? Ceiling to window start is 13 inches. Further I cannot add a ceiling exhaust fan as I have a 2nd floor above and no attic access. I have attached the image with details