Well, I tried that method, starting a new game, choose a default English character, switch to Spain and spawn in Portobelo (I had to do this several times until I got a Portobelo spawn), go to sea, worldmap, but no crash; I made it all the way to Cuba.
Can you reproduce if you save at port, load the save, and does it still crash? If so, send me that save along with your save folder options.