Advice for putting in a permanent sleeve for a room air conditioner

[Kolesar]

We currently use a 6000 BTU/hr window air conditioner to cool our north bedroom. We would like to replace the windows, and I was thinking of replacing the two double hung windows with one, smaller awning window. (Smaller for less heat loss and more privacy).

I don't think that awning windows are suitable for window air condiitoners: one would have to remove the sash and build an elaborate adapter mounting. So, a permanent air conditioning sleeve that could be blocked with an insulated panel for winter sounds best.

I have seen big casement window air conditioner sleeves. Those are for 8000 BTU/hr air conditioners and larger. I expect that I would want something smaller that would fit the air conditioner that I have or another 6000 BTU/hr air conditioner.

I have never seen such an installation. I would like to get a carpenter to rebuild the wall and install the window and the air conditioner mounting, but I don't really know what I am asking for. For example, would this be trimmmed with casing like as was done with the other windows in the house? How does the blocking panel work? How does one wrap the installation with plastic/Tyvek(R) to make it waterproof? Intuitively, the air conditioner should be at a rather low height so that it is easy to handle biennially. Are there premade sleeves for an air conditioner?

It should be mentioned that I would need double exposure aluminum siding to be torn back and for a smaller window to be framed and trimmed from the outside.

Advice anyone? thanks