Something no one else has mentioned yet, if you take some of them, check them in at the U.S. side of the border. They have a form they will fill out. If you don't, there is a chance they will say you may have bought them in Canada and U.S. Border Patrol will charge you taxes on them. With the form, you have proof that you brought them in and out of Canada.
I did the ferry thing in the winter of 2008 going back to the lower 48. I'd recommend you fill up in WA or at least in Haines. The stretch from Haines to Haines Junction took a lot more gas than I expected. The wind up there is brutal and killed my gas milage. Make sure your spare is full, I'll let you guess why I know that one. I had a lot of 12ga target loads and 222 Mag rounds along with other ammo and it wasn't an issue either side.
As a side note, people think jeeps are great in the snow and they are pretty good in the powder type stuff, but they usually suck on icy roads that you are sure to come across in the trip. Studded tires are recommended, but not all states allow you to use them and other limit the time of year that you can. Are you going to Fort Wainright(sp) or Fort Richardson? Ft Wainright is in a colder part of the state and you will need a core heater for your engine or you may have starting issues. Make sure your antifreeze is fresh.
