If we want to be pedantic about it, then it is enough that a person who lives in a area where weed is legal and they consider to visit a area where it is not legal and don't explicitly declare that they intend to leave the weed at home. You don't need to add the "massive amount" aspect, as it would be a crime if they made the trip, which then makes it a conspiracy.

But that is not how the law get enforced, and people don't get extradited for crimes like that. They don't even get extradited when you have evidence of committed crimes like speeding, which maximum punishment is longer than cracking a password.