How many resonating structures of Carbon Monoxide are there?
You have said it yourself. There are many possible resonance structures but most of them have a negligible contribution to the overall structure. Your proposed structure is one of them.

The major resonance contributors of carbon monoxide are: $$\ce{\!\overset{\ominus}{C}#\overset{\oplus}{O}\! ~&lt;-&gt;~ \!C=O\! ~&lt;-&gt;~\!\overset{\oplus}{C}-\overset{\ominus}{O}\!}$$