It really depends on where you are. There are places where you could do that, but many where it just would not be very possible. The feasibility of dropping and being safe really means being in sheltered waters. The OP was writing about dying at sea. Way different, at least to me.
For instance, between San Francisco
and the Channel Islands (off Santa Barbara), it would be very easy to be 3 hrs. away from a safe entry to a harbor, possibly more. IMO, a helper dog might be very good company for him, but he should not be out there skippering in crowded areas. It is a situation fraught with peril for the OP, if he has the seizure and survives, but some children
are killed by his out of control boat, imagine the lawsuits and what that would do to his quality of life. This very discussion on CF would be used against him.
Incidentally, I have wondered all along if this were a troll, we're certainly providing an author with lots of dialog and plot twists.