Puerto Rico: What was it like in the 40s?

If you can get hold of the second DVD in this set, it looks perfect for you:

http://www.qualityinformationpublis...ountriesoflatinamericaincludingcubachile.aspx

Part of it seems to be in the public domain and available here:
http://www.archive.org/details/Democrac1940

I found these by Googling "puerto rico 1940s movie" since I thought a movie with that setting might be a good way to start getting a feel for the atmosphere. As for the businessman, it probably depends on what his business is and what are his ideals or lack thereof. A lot of sleazy moneyed types made Cuba into their personal playground around that time, I know. I wouldn't be surprised if shady US businessmen also set up dealings in PR conveniently away from closer scrutiny, but on the other hand probably there were others with much more laudable motives.

I would look at Operation Bootstrap, which started in 1948 and tried to convert the island from an agrarian economy to a manufacturing economy.

Like most Caribbean islands, the wealthy live close to the ocean and the poorer people lived in the center of the island. One reason goats are popular for food is because there isn't sufficient flat land to raise cattle, and poor people who raised their own livestock live in hilly areas.

Citizens of Puerto Rico don't pay federal income tax, unless they work for the federal government (including military) or the income is generated on the mainland. So a wealthy person with investments and companies on the mainland wouldn't get any tax benefit to living in PR.

The cost of living is lower, so your MC could have a mansion staffed with dozens of servants.

He needs to be able to speak Spanish. And he has to have some reason to move to the Caribbean while maintaining US citizenship and residency.