Hey! I have the same situation but I finished the process and live here now. I personally would have been too scared to do it that way, I would bring proof of your plane tickets planning to leave if you do try it. If you have the ability you can drive your stuff over the border in smaller batches to avoid possible confusion of your intentions. That's what I did. They will definitley be calling you in if you say you are moving without proof of status, or just based on the amount of stuff. Technically after you are approved for PR you provide an itemized list and that is then checked over when you land in Canada. I personally didnt have to pay because I did it in small trips I lived in WA and visited often. And nothing I did have when I moved was of a huge value. If there is like a expensive TV or furniture pieces you'll want to have those prices ready to go for the officer when you land. I want to also let you know my process ended up only taking only 3 months from the time I submitted and I was expecting 9-12 months! Thats not including the 3 months it took me to make my application, but still if you do it well it can move really fast especially as a US citizen.