Mexico travel with an expired US DL license...

In Guerrero, I'd say just get a license here. Pay the 1,000p for a 5 year license, prove your blood type, your address and away you go. Provide an address from a rent receipt at the RV park, and you are in.

Many years ago, we carried expired drivers licenses in case we got stopped. We got stopped in San Miguel de Allende, the transito said, in perfect English that is was expired. We acted shocked, and in disgust, he just sent us on our way.

Good luck with your decision.