As far as I know for Coastal Cruising the furthest places in North America for fuel are:
Turtle Bay Baja to Cabo Baja at something just over 400NM, BUT fuel is available 1/2 way there at Mag Bay.
Yakutat Alaska to Seward Alaska at 310 NM or Yakutat Alaska to either Whittier, or Cordova Alaska at 260NM.
I have not found anywhere in North America that is over 160NM where you could not safely sit out bad weather.
In and from Alaska our longest legs were Kodiak to Sitka and Sitka to Port Angeles but those both could have been avoided. The longest we found no way around, and perhaps someone else has, was Ensenada to Cabo San Lucas. If I recall correctly, that's about 680 nm. There may be a way to get fuel by truck in between. We didn't need it so didn't research it.