If the wood is too wet, it may not finish very smoothly. You may need to air dry it a little. I suspect the climate of Costa Rica makes it hard to dry wood to very dry. A large diameter straight bit will do the job and straight bits are among the cheapest. How large you can run depends on the hardness of the wood, the depth of cut, and the feed speed.
Someone I consider a master woodworker once told me that a master woodworker is not someone who never makes mistakes. He is someone who is able to cover them up so that no one can tell.