I found this on the NYS DMV website:
Can I register my pick-up truck as a 'passenger' class vehicle?
Yes. Your pick-up truck can qualify for passenger class plates if it meets certain conditions, depending on its unladen weight.
If you have a modified or unmodified pick-up truck with an unladen weight less than 6,001 lbs., then you may register it in the passenger class if it meets the following conditions:
the pick-up truck does not have any business advertisements, and
the pick-up is used exclusively for non-commercial purposes
If you have a modified pick-up truck with an unladen weight greater than 6,000 lbs., then you may register it in the passenger class if it meets the following conditions:
the pick-up truck does not have any business advertisements and is used exclusively for non-commercial purposes
a camper top having one or more side windows completely encloses the truck bed,
the pick-up truck has seats, seat fittings, or camping equipment installed in the truck bed ('camping equipment' indicates that you have a bed, a stove, or a refrigerator in the vehicle)
NOTE: These modifications must be permanent. If you use the pick-up truck without the required modifications, then you must register it in the commercial registration class.
You are not required to apply for passenger class plates for your pick-up. You can use commercial plates.
