...and they look like a Land Cruiser Prado 120, to them it will be a Land Cruiser Prado 120, not a Lexus. they dont have Lexus down there, so if you dont draw attention to yourself and spend like $100 and rebadge it to a Prado from a GX 95+% of them wont be the wiser...
as far as the gringo thing goes, any american that far south getting out of a vehicle will get attention no matter what vehicle they exit. we are speaking central and south america, not Mexico. in Mexico americans are quite prevalent, dare i say everyday occurrences, the further south you go the less and less... that also goes with the Lexus, in Mexico they will know a Lexus is and know(read think) it means money. the further south you go the lines get blurred and start going more to the Prado. Mexico will be the hump to get over, from there i am willing to say everything will get easier. -imo less chance of kidnapping(further away from home and harder to orchestrate exchange ect), and unlike Mexico they people understand more and more that you are their "cash cow" and a good source of commerce, they take you or your rig away and you are not gonna be paying anyone anything or ever coming back. in Mexico they dont care, again a gringo is a dime a dozen and "another one is right around the corner" if they dont get what they want.
having owned a 3rd gen 4runner and built it up and used it for all sorts of stuff from daily driver to exploring rig to wheeling/camping, i can tell you id rather take my GX on this trip hands down over the 4runner. the Lexus is more comfortable, just as capable and the chassis is much improved. not to mention its gonna be easier to break into or steal a 3rd gen 4runner. and no a 3rd gen does not get decent mileage, my GX gets better mileage and has more power and has more room. not to mention that 3rd gen 4runners are not as popular as Land Cruisers down there, and so it would "stand out" just as much, if not more than a GX.