You want to fly over water for extended period-so a twin is mandatory, probably (depending upon regulations) even floats=heavy aircraft.
I suggest you focus on your funding first-with 2 aircraft, we are looking at 5 Million USD at least to start going.....plus another 500.000 in annual salaries, probably 250.000 in overhaul, same for insurance, and probably around 250.000 in fuel..
So you need to get around 1-2 Million USD EVERY YEAR on top of your 5 Million to start with...
Once you get the money,it will take you 2-3 years to get to operational stage-by that time, the migration crisis will have sorted itself out...