Well, the weather you're facing down there sounds fairly similar to the majority of what we have here in Florida. 40-50 F (which is very close to the conversion for 5-10 C) is fairly normal for our "winters". It might get lower than that for a month of nights a year, here.
My experience with that says that a basic CCF pad will work at those temperatures, though an underquilt will be more comfortable (you don't have to fight with the pad in the hammock that way). Let us know how everything works out for you!