I’ll spend four weeks in Colombia and three in Ecuador.)
If possible, I do wish to avoid high (or at least peak) season so that things won’t become too expensive.
I think I have to do Peru in November (i.e., AFTER arriving in Colombia in mid-September and continuing to Ecuador), since if I go directly to Peru from Europe, I’ll likely have visa problems with Chile and Argentina. In any case it’ll be much safer for me to try to sort that out ONE COUNTRY IN ADVANCE (like in Ecuador).
Since the only thing in Peru that I feel I need to see but haven’t is Machu Picchu, I’ll limit my stay in Peru (mainly Lima) for roughly 2 weeks or a bit more than that; I’ll plan the flights to and back from Cuzco (with round-trip trains from somewhere to Aguas Calientes) at the middle of the stay, preferably not too close to my direct flight to Easter Island