Still seems like a smart idea to get a PCR test within 72 hours, regardless of vaccination status. Given the website ambiguity and frequently-changing local govt policies, it would be foolish to book such a long trip and then be turned away by the airline or immigration authorities for whatever reason.

(Also, you wouldn't want to be asymptomatic/presymptomatic and positive for Covid and not find out until you were already in Peru! Better to find out in advance and just postpone your trip)