I know it's pretty easy to get one in Washington, and not hard to justify. Obviously knowing someone with an address where you can have it sent to makes it easier. Canadians spend a lot of time in th US so it's not uncommon to need ID and it is actually encouraged if your there more than a week or so. Just say tell them you spend a lot of time in the US and it would make your life easier to have a stateside ID while you are there. Worked for a bunch of people I know.
As far as working in Vancouver, if your really interested I can get you in touch with the right people. Usually if you come for a bunch of scenes travel can be worked out. Hit me up if you want some advice. Incidentally I'll be in TO and Montreal this month. Drop me a line.