So I just read your post to my DH, who is retired AF... He said those MRE's have between 3000-3500 calories in them.

He said they are made for a soldier to be able to sustain himself on one a day if he has to.... You might want to forego those in the future.
We drove down from Alaska to Utah using the Montana route last August when we moved. There are stores along the way and as Linda said, they do have fresh food...

However, the stores can be pretty few and far between along the road you'll be traveling. (You'll find a Safeway about every 300 miles or so.) We found fresh food was more expensive once you leave the Lower 48... I'd try to be fully stocked before you enter CAN. Customs will not allow you to bring meat from CAN into the US, so just buy what meat you'll need while in CAN.
If you haven't purchase a "Mile Post", I would really recommend it. It has a list mile by mile of where everything is along the road. It's really helpful for planning camping stops, getting gas and replenishing supplies both in Alaska and on the way there. Another great reference guide is "Traveler's Guide to Alaskan Camping".
If you'd like to chat more about your trip, feel free to send me an email at theloves_on_the_road AT hotmail dot com.