I have gone into Canada with rifles a few times. The 909 form, as you well know, is pretty straight forward. I have never had a problem crossing with them. Sometimes they have looked at the guns (going through the motions drama) other times they did not ask to see them
You can expect the border agents to ask you to come inside and pay the money. Be sure that you do not sign your signature on the CAFC 909 untill you are being witnessed by a border agent I do not remember just why that is, but they want to see you sign it. Also, in case you are not aware, there are different prices for how long the form is good for. I'd go with the one that is for the shortest period of time. I don't recall how long exactly it is, but I do know it's plenty long enough for you to drive through and get to Alaska before it expires.
Not sure of your situation and how many guns are involved, but shipping them to yourself (from 48 to Ak) would/could be an option. At least the Kanuck government would not be getting money from you, not to mention the paperwork trail that they keep on your guns.
Truely one of the stupidest, most useless, fiscaly irresonsible and expensive laws ever enacted on planet earth.
The more I think about it, the more i say mail them to yourself, just out of principal alone. JMO
Good luck