To clarify a bit.
The overwater flying portion is to and from the location. Once there it will all be over land/within gliding distance.
The trip overwater is about 240NM (about 200 over water) which will give an estimated flight time of around 2hrs each way.
The R44 is definitely a viable option, never knew they existed with floats. Like I initially wrote, I am completely unfamiliar with helicopters, so no particular reason for locking the focus on a B206.
Could the ferry flight be completed with the doors in place and the remove them once on location? Can it be done with use of simple tools or is an engineer required?