Window Plug for very big window possible ?

Hey studio people, hopefully someone knows a solution to this. for several years I used the recording room to record different types of music and had the room, which I not own but rent, all on my own (just for recording, mixing is done elsewhere) . Because of the changed financial situation I need to share the room with a good friend of mine. Problem here is : I intentionally do not have any windows in there because of traffic noise outside. But my friend, because she gives lessons in there to about 20 people per session, needs (wants) a window in there for daylight and air exchange and we also need to make the room bigger to fit all of those people. So we thought about removing the wall to the next room to get more space and a window. She uses the room on weekdays and I use it on weekends. I mainly record vocals in there and sometimes an acoustic guitar and some percussion but never full bands. I´m personally not a fan of tight vocal booths and prefer much more recording people singing in the same room that I am. So I am trying to stop the traffic noise coming from the window in a different way to be able to fully use this nice spacious room. The wall which we may tear down is a simple build sheetrock wall on steel studs with 1/2 inch sheetrock on either side filled with glasswool. As you maybe can see in the pictures the wall is not build up till the real ceiling but just under the false ceiling which was installed much much earlier. The isolation it gives me is already enough for my purpose (still some low frequency noise which comes through the whole building structure but I think its not possible to remove them without spending much more money). Do you think a window plug could give me the same isolation as the sheetrock wall and still is removable by one person (maybe build in several pieces) ? Or do I have to build something else not removable ? I am trying not to invest large amount of money cause the room is only for rent and we never know how long we can keep it. I am living in Germany and a solution to this problem may cost up to 500$ USD. the window is about 7 feet wide and 9 feet high. Thanks for reading all of my problems :-) cheers, Heiko Here is a rough sketch of the situation : This is the described big window, it´s from floor to ceiling : A closer view : Still closer : Close up how the window is build : Looking at the wall that will be removed : Looking at the wall from the recording room side :

maybe adding a pair of hinged panels (say 2x 19mm MDF on 1x 19mm plywood) with seals on a simple wood frame lining the opening (basically solid french doors) should do the trick and be easy enough to construct. some cloth covered absorbers on the doors to damp the air cavity.