AND I might add ...

(1) you can get away with a single entry visa and then leave and return from multiple entry points (so long as they are not EZE) -- I entered at EZE, left at Iguazu by car, returned at Iguazu by car, left at BA ferry port, returned at BA ferry port all within a week or so on a single entry visa

(2) the whole tourist card thing can be somewhat lax -- on arrival at EZE the customs agent mistakenly gave me back my customs declaration but no tourist card, I was tired and confused, speaking virtually no Spanish so I didn't catch this error -- when returning to Argentina at Iguazu Apr 6, my taxi driver had to explain things to the customs guy there who simply wrote me up a new tourist card -- then when transiting back from Uruguay Apr 7 I somehow ended up with yet another 'spare' tourist card -- upon leaving EZE for LIM I handed the customs agent the Apr 6 card because it looked like the example they had pictures of ... he looked thru my passport stamps multiple times, then at the card, then at me, finally gives this huge sigh, stamps my exit stamp while shaking his head without asking me a single question. LOL sometimes being a friendly and innocent looking young solo traveller is a good thing!

Of course, your results may vary!