I just saw that two Americans sold their KLRs fairly easily in a Zona Franca (Punta Arenas or Iquique). Here’s the process, per their ADV post:

We sold one bike to a foreigner and one bike to a Chilean. The process for selling the bike to a Chilean is quite straight forward if you are in a Zona Franca (Punta Arenas or Iquique). Step one is go to a notary to create a document of sale. Step two is go Aduana with your documents and buyer and seller, have them create all the appropriate paper work, and then drive the bike to aduana storage and leave it there. For the seller, your part is done here. TVIP cancelled and situation noted on back of PDI document.

We had a tougher time selling to a foreigner, but now that we know the drill it would be easier. At the notary we needed to create not only a sale document but also a power to use document. We returned to aduana with these documents and I believe the original TVIP was conserved but with a note from the aduana director permitting exit of the country. The buyer left the country and entered Argentina the following day without issue.

Lots of speculation of the internet about selling bikes down south; we found the process quite simple and got excellent prices. We had many offers from Argentinians, Chileans and foreigners. In some cases we could have sold the bike without papers, and in some with. It just so happened that the best offers we got were also folks wanting a legal transfer. It helps to have time, patience, and the language.