CA Traveler, I realize there aren't any Flying J/Pilot stations on the Alaska Hiway. I used that trip as an example of the gallons consumed and price paid on a real trip and how much savings one would see. As you found out, the saving compared to the rest of the costs were pretty minimal.
No, I didn't get the AFD lock card in Canada. And the savings you saw with your 5% cash back matches my example.
Unfortunately not everyone qualifies for a Penfed card that you use though. There might be some similar cards out there that are similar. Likewsie on cards that do or don't charge extra fees when used in Canada.
Anyway, on my trip north I made up for all the savings I didn't get on fuel by getting free camping for the summer at a friend's place - electric and water included and I've been assured that on my next visit he'll have a dump station too. :-)