Talk about hiding a back-up key somewhere in the RV to prevent self-lockout, I just now remember this encounter.
We have crossed the border many times, but this was the first time in a MH, and of course a MH has many nooks and crannies where "stuff' might be hidden.
When we crossed from the US to Canada, the Canadian custom did not give us much problem. I knew we were not supposed to bring in more than a certain amount of booze. Surely, they asked us about that, and of course any weapon, and that was pretty much it.
Coming back into the US, the US custom spent more time than when we were re-entering the US in a car. Mainly, they asked a lot of questions just to see our reactions. Following is part of the conversation that took place.
US Custom: "What did you buy or bring back from Canada?"
Me: "We still have some meat packages, and some fruits."
US Custom: "How about marijuana?"
Me laughing: "No, no marijuana!".
US Custom: "So, is this your own RV?"
Me: "Yes."
US Custom: "How long have you had it? How many trips?"
Me: "A little more than 3 years. This is my 3rd annual summer trip."
US Custom: "Any modifications?"
Me: "Oh yes, I added solar panel, extra batteries, charging systems..."
US Custom: "How about secret compartments?"
I bursted out laughing...
They did climb on board to look into the frig and took some lemons we still had left. Said it did not matter if we bought in the States and were bringing them back. Citrus not allowed regardless of source. Some other fruits OK if had stickers showing origin. Rules change from time to time, according to who-knows-what.