Did you already book lodging??? At least in El Chalten (Estancia Bonanza) they told us they finish up end of March into April. One or two gauchos live on-site thru the winter, but the place is essential closed. The whole town they said pretty much shuts down. Very few year round residents. Everyone we met in-town or on the estancia was from Cordoba, Mendoza, Buenos Aires. El Calafate, not sure, I suspect its about the same. Unless its' a ski destination, like Bariloche, most close. I really think late May is too late. Can you not change your dates??

We loved our trip so much, we plan to come back again next year. Everybody said their favorite time was "autumn" which is Feb into March. Cooler, brisk, trees do change color.