Yes, the bed is quite free draining. After reading up on the subject, I think you are correct Mum, the problem lies with water (uneven supply). For a month before the BER troubles, we had hot dry weather. I watered of course, the plants never wilted, looked great, and did set fruit, so I thought I was on top of it. Then we had the remnants of a tropical storm come through for 3 or 4 straight days. I started seeing a lot of BER after that.
Thanks for the advice on varieties, I will see which of those might be available here. I've also downloaded as many BER-related bulletins as I can find from agricultural extension offices in various US states. I did supply calcium early, as advised, but probably should have stopped supplying NPK fertilizer, to slow the foliar growth, which may be robbing CA from the fruit, causing BER.
Live and learn, right?