JP, I'm beginning to think that we need to start a lobby to get law enforcement to understand the laws they are enforcing. Here's a relevant document from the New York DMV:
http://www.nydmv.state.ny.us/broch/cdl/cdl10sec01.pdf
Read 1.1 in that document and tell me if that doesn't sound like the 12,000# trailer would require a CDL only if the GCRW (truck and trailer combined) is over 26,000. Sure looks like it to me.