Here is the definition of a "truck" and a "Commercial vehicle" in NY.
https://www1.nyc.gov/html/dot/html/m...ckorcomm.shtml
I don't think windows have anything to do with it. I also think that a long time ago, in NJ and NY if you bought a pickup truck or van, you were forced to register it with commercial plates. I think this changed at some point because pickup trucks became personal vehicles that could haul a family around.(quad cabs and the like)
So the rule(law?) that no commercial vehicles, trucks or tractor trailers are allowed on parkways means that your van should be allowed, regardless of windows.
I would interpret it this way, your van is not a "truck" because it does not have 6 wheels, nor does it have 3 axles. I would also say your van is not a commercial vehicle because it does not have commercial plates. I would say your van is not a tractor trailer, because well, it isn't, ha!
Just my 2 cents.