Good thinkin'. I like both fixes. When we took delivery of our camper, I wasn't in love with this window and wondered about what I could do. I didn't think about it too long, after our first night of camping in 20 degree weather.
We have one of these windows in the cab-over bed of our truck camper. Unlike the other windows, it does not have a storm window for insulation. Last Winter, I cut some 2", pink foam insulation material to size and friction fit it between the valance and the window's operating lever. It's a pretty good fit and certainly helped when it was 5 degrees Wally Docking en route to Texas the first of February. The lever and the thought of an alternative opening method soon became very low on my to-do list. I figure the insulation will have the same affect in The Keys the end of August, helping to keep the cab-over cooler. Our windows are tinted, so the pink isn't visible from outside.
