First, let me start by saying that this is only my experience. One thing we learned in 12 years of being full time in Mexico is that there really are no hard and fast rules. What happened to me may not be what happens to you at all.
There are a lot of 'experts' down there. They are wrong as often as they're right when it comes to how laws are enforced there. It's really a crapshoot.
I have had 3 boats in Mexico. 1 had a HIN, two did not. I actually had both of the non-hin boats down there at the same time the AGACE raids happened, one in La Cruz, the other in Paradise Village. Paradise village was not inspected, La Cruz was. The boat that was in La Cruz did not get inspected because she was actually in the travellift when the inspections occurred. I do not know for sure that I would have stayed off the impound list if she had been checked.
Anyway, in every case, I have used the vessel's official number on the TIP. All my boats that that number engraved into the boat in accordance with USCG rules, so I just went with that. I do know some other folks who have done the same thing, and they got through the inspections just fine.
So, assuming that you have something similar permanently affixed on your boat, I would suggest using that number rather than leaving the HIN spot blank on the TIP. I believe that this will satisfy pretty much any inspector. One thing we learned from the AGACE episode was that they really didn't know much. You should be ok.
If there's no permanent marking on your boat, I'm not sure what the best course of action would be. The people in San Carlos
should be able to advise in this case.
Good luck. My guess is that they're going to be quite a bit more flexible this time around after all the bad press from the last episode.
Just one guy's opinion, mind you.
Good luck, TJ