Found this hand-made wraught-iron at our local salvage yard (George’s); too small for the window, but too nice to pass up. After a bit of head scratching and measuring, and looking through my dwindling metal scrap, I came up with a solution.
During the summer I leave the window open and mount a fan in the ceiling access panel to draw cool air in and push the heat out. This takes the worry out of having the window open out there.
Sturdy enough for pull-ups!
My metal cutting blades are all dull, so cutting the steel was loud and took some grinding. Predrilling holes for bolts, then welding it all together. Then a fresh coat of paint. Then mounting it. An afternoon of man-craft.