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
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.