I'm planning to fly MDE-MEX-LAX on Viva Aerobus in July. The fare is good but it comes with a 19h30 layover at night (0105 till 2035) in MEX.

I was hoping to put the layover to good use: a short sleep in a hotel and then some sightseeing of places I missed out on my first visit.

I've checked the taxes that have been quoted on the flight MDE-MEX-LAX on Viva Aerobus and Volaris and Aeromexico. Being on transit for less than 24h, the Mexican Tourist Tax (Code "UK", DNI – Derecho No Inmigrante) will not be collected as part of the ticket.

QUESTIONS:

1) Will I get charged the DNI Tax manually if I leave the airport (enter Mexico) on my long transit, go sleep in a hotel, do sightseeing and then fly out after about 18 hours?
2) Where might that be collected? Eg. arrival immigration, departure immigration?

Thanks in advance.