If you book your trip through a tour operator or hotel, you can use your credit card without problem. If you arrange your trip directly with a guide, you will usually need to pay with cash.
I have used several guides on AC. The best guide I have used is Pedro (Pete) Graniel. First rate equipment, including boats, and does both offshore, reef and inshore (tarpon, etc.) Keeps his boat just south of town. Ask anyone how to contact him. He's well known.