To the OP- Since this Thanksgiving will have personal meaning to the two of you, would you consider attempting a dinner at home? Even if it's not perfect with all the trimmings, it'd probably be very sweet and more personal than just a crowded restaurants.
I know that finding (and cooking!) a turkey here would be a real challenge, but perhaps you could think of an alternative way to make it a "Thanksgiving al estilo porteño"? Potatoes, sweet potatoes, corn, and some veggies can be found here, for example. Perhaps you could think of your own favorite dishes, even if they are not "traditional"... I don't know, just a suggestion, but worth considering!
I am mentioning this because last Thanksgiving was the first one I celebrated with my husband during our first year of marriage. We ate with my in-laws, and I explained that we have a tradition of going around and each person says what they are really thankful for, it was super-sweet! We all had a great deal to be thankful for!
To make this "imperfect" Thanksgiving dinner beyond perfect was my mother-in-law and her good intentions! She baked a chicken since turkey was too difficult to get a hold of. I also saw her cooking a blueberry sauce on the stove top. I asked her if we were going to eat it with ice cream. "No," she told me. "I read that in the US, you guys eat turkey with blueberry sauce." Hahaha! I can't say I blame her, I looked in various dictionaries and on Wordreference.com, and "cranberry" in Spanish is only translated as "blueberry," which is NOT the same thing!!!
So as a family, we at a Porteño-style Thanksgiving, with the main dish being chicken with blueberry sauce! Jaja! In my opinion, that TRUMPS Kansas or any other Thanksgiving celebration down here!