Your post could have been written by me a year or two ago. Contributors in this TTOL forum led us to get a Capital One card for SXM trips and we've never looked back. Just paid my latest SXM bill yesterday, and we paid the market exchange rate on the day the transaction was processed. We also get Rewards/Points. Love it.
On their website you can even login and advise them you'll be travelling and to expect the card to be used in places like SXM during a range of specific dates, thus you won't get any surprise declines, holds, alerts or hassles that can sometimes occur when your card suddenly starts getting used in a foreign land.
The only thing that's a pain is wading through the array of ever changing Capital One cards available, and then finding the one that best suits your needs. Ours were minimal... No Annual Fee, No Foreign Transaction Fee.