Definitely need to learn about and play the nighttime calms and katabatic winds. Frank Virgintino's book - Thinking Man's Guide to Voyages South - is a must-read, in addition to Van Sant's.
I've not done south coast of Cuba, but followed Frank's advice in a midwinter passage
from the Bahamas
to the BVI, and was very happy with the fast (despite longer distance) & easy passage
and the interesting stops along the way. There's another, older CF blog that might be worth reviewing also: The Thinking Man's Guide to Voyages South
and you might email
Frank directly - he was very friendly, responsive and helpful, both during our trip planning and once we had the pleasure of his friendship in person when we found ourselves in the next slip over at ZarPar in Boca Chica.
The eastern end of the south side of Cuba is a very inhospitable coast, so you'll want to plan your route
windows very carefully. The Windward Passage was great to reach thru heading south, but wouldn't have been any fun at all heading east from Cuba. Island hopping from Caymans to Jamaica and on up to Haiti
while playing the lees and calms probably is a much better idea.