If I understand correctly, you plan to cross the
Panama Canal from the Pacific to the
Caribbean.
From there until Fortaleza,
Brazil, you have 3000 mi to travel uphill, against
wind and
current (!!!).
From Fortaleza to Cape Horn the
navigation is more or less normal, and is a well traveled
route, plenty of blogs and info about it.
If, on the other hand, you stay on the Pacific,
wind and currents are going north near the SA coast. I remember a
boat named Sequitur has a blog about this
route.
Winters are not always gentle south of 40S.
Good luck with your planning.
PS: I just realized you are in a
motor boat. In this case wind and currents are less critical.