I saw a Dominican Republic site but really wasn't interested after seeing the providers. Plus, they offer bare back sex if you can provide an AIDS test. Thought that was crazy. They had packages for a certain number of nights, one girl per day, on girl in the morning and then a different girl at night and a certain type of room per price. I can PM you the link if you'd like since TER may not allow the posting of a link. It would be interesting to hear from others about their erotic vacations since I travel to South America once per year.  

My suggestion is to...

Ask GaGambler. He is the expert on being a man whore on such ventures
Have fun wherever you go

Jaco Beach. I understand you can do it on your own . No tour op needed. German FKK clubs get a lot of talk on the various boards.

Try an extended vacation and fly to Thailand or the Philippines.  Or both, which I did...Highly recommended!  
PM if you have questions.