bchaps, I respectfully submit the problem is not your wife's problem, but yours. You are fearful of being out at sea, injured, or seriously ill, with your wife unable to get you back to port. That fear is your problem.
Two responses to that. The first, to be brutal about it, is that is one of the prices of going sailing. If the price is too steep, stay at home. How boring. The second response is that if you are going to the Bahamas, you will be in good hands. In cruising through the Bahamas I have listened in on two rescues by the Bahamas rescue team. Both times were very impressive, and very efficient. No fuss, no loud voices or hurried speech, just quiet competence. Both times they flew a 172 to the area, spotted the problem and then homed a surface craft in on the 172. If your wife got on the radio with a serious problem, somebody would be alongside in a short hour or so.
Have you played "You have the conn." game with your wife. In other words, you sail the boat, but she gives you the helm orders. Might build her confidence without her having the responsibility. YOU WILL NEED THIS SKILL in the Bahamas, as you navigate the shallows, with her on the bow finding the channel, and you steering at her direction.