That's a good looking van Larry, what are the windows you're planning on installing?
Two years ago I replaced a conversion van RV window with sheet metal on one side, and I've driven around without that horizontal support ever since. The panel is much less rigid without the window or the support, and probably contributes to increased vibration and noise. In my case, I’m adding the vertical support back for reduced vibration, but also since I’m painting that side I’d like the rigidity for block sanding.
If I was going to add a small window where the support ran, I'd only take out part of it and add a horizontal cross piece to reinforce what remains. On the other hand, maybe Kilmat or something similar would be sufficient to counteract the noise.
Not the definitive answer you were probably looking for, but something to consider.
