Have taken the trip and now back.

The day I arrived in BA I asked the hotel clerk where to get the dolar blue rate and she told me the hotel would buy US dollars 9 to 1. I said OK. I walked down Florida Street and there are touts that were offering 9.5 to 1, but I was a little dubious, so I didn't trade. I traded $500 US for 4,500 pesos at the hotel.

Traveled to Cordoba and traded twice. Once for 9.5 to 1 and again at 9.2 to 1.

Traveled to Mendoza and traded 9 to 1.

I did all the trades in the daytime and inspected every bill (they have a watermark). I was situationally aware when walking away and cautious.

I went back to BA and had about 1200 pesos I want to trade back to dollars. I bought US dollars for 10 pesos each. The regular exchange places won't trade unless you have a document of where you got the money.

Argentina is not the cheap place it was even just a few years ago. At the official exchange rate it would have been expensive, but getting 50% more by trading cash makes the trip more affordable.