I’d be careful that cheap 12V hookah previously linked on this thread...
That's a concern, but I'd be more worried about the operator/user. Go to a PADI school and get certified. Snorkeling vs working with air lines under your boat are 2 different things even at 6'. Pick a nice local, you and the admiral could get certified in MX or the South Pacific? It would be a great vacation and you'll have trained support staff as well.
Shark jaws or similar might be all you need for the occasional line on the prop shaft.
I think using shark jaws is too dangerous and, of course, a mask and tank are quite "dull and cumbersome." (Sorry! That's the first thing that popped into my mind. )What are shark jaws?.....Can I just use my snorkel mask to cut a line off the prop or do I need a compressor or tank