Honestly all the scenarios about "what if all I have is pesos" don't figure into the government's policies. If you're a real tourist, you have access to foreign currency, without exception. If you don't, well plan better next time.
All of these problems "what if all I have is pesos?" sounds like a permatourist problem and if you think the government is worried about how to make permatourists happy, then you've got another thing coming.