Would it work to have a POD where Massachusetts, New York, and one other state does not approve the constitution? Would there be any problems with this?
It is highly possible for any one of the 13 colonies to disagree with a certain aspect of the constitution.
The first problems I can see would be the delay, as the war is coming to a close, the 13 colonies want to bring about a quick constitution, as to, fix their political and economical structure before becoming fully independent.
Also if one colony finds a problem and does not unite it could cause problems else where, for example, if North Carolina, disagrees, how does South Carolina and Georgia unite with the rest?