Hola, Rob. I just called the Cihuatlan General Hospital, vaccination line #2, and the clerk said that you need to present ID and proof of two prior vaccinations from here or wherever. Boosters are available until Thursday.

Sounds like you do not have to have a CURP #. You can call this number and verify this information. You will need to know some Spanish, I think.
315 355 2171, line 2. Good luck, Cruz