Runway
Approvals needed for each place you go to. This takes up most of the pilot's time. Most of the European countries are very good and are used to helicopters based on ships.
You specifically mentioned Thailand. For me, the most difficult place to get an approval to operate to and from the ship.
Salt/corrosion problems are a real threat and washing, washing and more washing is required.
$$ are good but alot of waiting around.
