Ok I have had first hand experience with the "Ship Stores" thing. First year we crossed into Canada, I gave them a listing of every drop of adult beverages and cigars.
Based on the advice from a very good Canadian I now do this and have not had any issues (Kind of).
I am a NEXUS card holder.
When I call in to Canadian customs I tell them what I have on board. Last year it was five 5ths of scotch, 5 gallon jugs of scotch, 3 bottles of Pendleton (so my buddy Crusty would have something to drink), 18 bottles of wine and 100 cigars.
Then I state this is ALL SHIP STORES AND FOR PRIVATE USE ONLY!!
Most of the time I pass through customs with no issues, unless you get a customs person from Ottawa. The don't know where the west coast of BC is let alone anything else.
Last summer, as I was crossing Dixon entrance heading south, I got a very young customs official. I think he was still on a sippy cup.
I told him the above and he started the "drill" with me. So here is how it went down:
CC: Sir, where was the wine made and the cost of each bottle?
Me: Most of the wine is from Oregon and Washington and cost on average about $12.
CC: Really $12? It wasn't more?
Me: OK, $20
CC: You have how much scotch?
Me: Enough to get through Canada. five-5ths and 5 gal jugs.
CC: Where was the scotch made?
Me: Huh, where was it made?
CC: Yes sir.
Me: (in my scotchish voice) It was made in Scotland lass. No one else knows how to make scotch!!
CC: Excuse me sir? You do know you will have to pay duty, right?
I then asked: You are aware this is ALL SHIP STORES AND FOR PRIVATE USE ONLY?
CC: Please hold
A few minutes later:
CC: I apologize sir, here is your customs number. Have a great day!!
