Hi Brian
We have just started our third season with our Magnum awning and have just changed to a new caravan. First of all the awning is excellent quality and still looks really good even though it had 90 days use last year and 45 the previous year.
Our first van was a Bailey Pageant Bordeaux and the awning rear pole just came to the edge of a window and with the padding on the rear of the awning this created a very good seal. The problem with the pole going over the window is that there would be a slight gap between the awning and the van above and below the window. But the carbonex poles have got a bit of "give" in them and with a short length foam in between, I think it should be OK. But these awnings can be quite flexible in where you put them, on our new van, which is an Adria Adora, we have the left side aligned with the caravan door, and as it opens on the right hand side we have to fasten it to the awning side to keep it open, but this does not cause any problems.
The awning is 10ft wide, so if you measure this against your van and see where the down poles would be, there may be more than one option, and then see how much your windows protrude from the van, this will give you a better idea.