I have been reading this, just didn't know what to add apart from you have gone above and beyond. Also demonstrates how important you are, and yes everything XW5 says is true. I know it's easy to think folk can react badly, but it's not in their interests and would only show them up as neglectful (assuming they have a good relationship with him).
Without seeming cold, regulars can disappear at any time for any reason, this is why whenever I stop accepting new clients it's only when I am really, really, 'overfull' and or the 'overfull' is prevent decent, good regulars from obtaining a booking within a sensible timescale, whilst maintaining a work/life balance, privacy and discretion. I also do not stop promoting myself, this also encourages regulars to book - keeps them interested and engaged so is usually worth the effort.