I'm not sure I concur with many of Terenz's points. In my view (based purely on reading the rules, never having tried to do it) the main problem with this is that the Circle Pacific fare has different prices based on total mileage tiers. The highest tier is the CIR29SA routing (which includes S America). Unfortunately your routing is over 36000 miles, so you are way over. I believe this is effectively how they stop you going to the East Coast.