I love Hispanic women ... man oh man! Almost insatiable beings, they are. They definitely know what their pussies are for ...
Playing to YOUR fantasy ... sure, why not?! Doesn't your wife deserve the BEST? Her sexual fulfillment is your responsibility ... either you do it, or you find someone that can. Isn't that what LOVE is all about? Tending to HER needs?
Now reality ... has she indicated she'd like to try a BBC? Has she been with any other men since you married her?
Just remember, once she's reached that new sexual plateau, she's not going to be content in returning to her normal sex life. That means, regardless of what you want later, she's probably going to continue wanting/getting what satisfies her. You won't be in control, and you'll then be a True Cuckold! Think you can handle THAT?