If you scroll down towards the bottom of the page on this ride report link you will see how one person dealt with your dilemma recently:
The reason nobody talks about how they got rid of their foreign bike in Argentina is because it is illegal. Just like nobody talks about where they stash drugs and money on their bike. Google is not your friend for this kind of information. And no, I don't stash drugs on my bike. I'm not saying where the money is.
I sympathize with your frustration, but rest assured that you will figure things out and it will all work out one way or another. You sound like a bright adventurous sort who is capable of thinking outside the box. Whether you get a police report declaring your bike totalled to get your TVIP cancelled and sell the bike privately to an Argentinian. Or sell it to a foreign traveller with a little help from photoshop. Or ride to Paraguay and sell it cheap. Selling to a foreign tourist will net you the most money. It has to be worth their while so forget about getting top dollar. Believe me, these things all work out in the end. In the mean time I suggest worrying about it obsessively. Just kidding.