Plan all three and let the weather on the day will dictate which one you execute. Discovery Helicopters in Atlin has fuel and it's easily doable from Bell 2, or even Smithers at altitude with a tailwind using Dease Lake as an alternate. It definitely doesn't hurt to carry a few jerry cans though. There's almost unlimited daylight so no reason to do anything silly. If you go the coast route and you don't have pop out floats, make sure you're wearing a life vest. Also know how to use a Canadian FSS RCO.