Thanks for all the detailed info and advice. It is much appreciated. We'll check the weather the day before and if its clear skies it will be the coastal route, otherwise sounds like the Trench route will work. We've got almost 500nm range which helps, but won't plan on doing more than 400 on a leg.
Sir Korsky, I'll definitely pop in to F Street Station. We going to be in Anchorage for a few days before mobilising to site so will make the most of it