We regularly fly over the border North and South with fuel drums onboard. So long as they are not plumbed into the aircraft fuel system, no-one really cares. Customs see so many aircraft coming and going this way that they really don't care.
Be sure to purchase an Alaska Supplement for flying in the State.
For flight planning try
this site. This will also give you a number of flight planning options, and pulls the weather for each at the same time.
Take care going through at this time of year. Bit more from the
Feds.