AIS and Nautical VHF
Never ever thought of those, good plan.
Just the VHF would be fine, as you will TX your mayday, with lat long from the sat, on 16... BUT remember Ch16 is not really monitored, as the nautical world has an automated system. a bit like selcall, (DSC), and all station distress messages are prefixed by special selcall bongs.
EPIRB is a good option, used by Nautical and Aeronautical types, but there might be registration problems, so sort this out early.
Imodium (!!!!) Sat phone, with GPS, is a good plan too, the normal Nokia not much use.
Glf