So knowing that they can get pesos using their bitcoin might hellp in persuading them to accept your bitcoin.

Otherwise, the method to get yourself some pesos for spending using "remittance to yourself" could be an alternative for you.

Looks like Remitly is who Coinbase is using for "last-mile" delivery into Mexico. So you can probably do that "remittance to yourself with cash pickup" if you have a Coinbase account too. I think, but I'm not sure.