Buying a North American bike in Santiago, Chile

[NewbRider]

Ok, first of all, I promise I've spent 3 hours looking into this already; I just need a conclusive answer. Thanks in advance!

Short story : landing in Santiago in 2 weeks. I'd like to purchase a bike which is already sort of arranged, from another traveller (also on HUBB!). It's a Florida registered bike in his name which he rode down. I plan to use overland titles (Alex) to get the bike registered in my name in Washington.

So the question is, I will end up in Santiago with the bike, and 2 different plates. I need to get it out of the country and back in, if I'm correct? Can I get a poder, ride it to the border and "check out" with the previous owners TIP and plates, then swap plates and come back in on my own TIP? Or do I need the previous owner to come with me?

What I'm really asking I guess is, is a TIP transferable? Or do I even need to transfer it if I have a poder?

Thanks, Dan