I made a mistake when I specced what I wanted at the converters with my windows.
The converters standard spec is opening O/S and fixed on N/S a they mainly convert full campers. Due to the known leaky window topic, I was going to change to fixed glass in both sides. (I'm just a kombi conversion and I forgot to tell then to fit fixed glass both sides,)
But- I have to say that what I have got suits me well as the kids now have better visibility out of the N/S window and whilst they don't like the reduced visibility/light from the opening window on the O/S, I like it if I am chilling in the van and just want a bit of air because I have noted that turning on ignition and faffing with front windows is a minor irritation once settled with seats rotated, etc.
Not had a summer with van yet, but I'm pretty sure one opening window will be useful in addition to the front windows.