You know how the car salesman goes to the back and discusses you price with the sales manager? And in reality he just went to the restroom or something? A lot of what goes on at the border, on both sides, is like that. They do certain things to provoke a reaction, and based on that reaction they may take other steps. If you are evasive or defensive in any way, they will take that as a sign to keep looking. While they are looking inside your truck or van, rest assured there is another officer looking at you and your reactions while waiting. Restless, nervous, fidgeting, looking around, rushed, these are not good body languages to project.
Instead, look bored, be cooperative but quiet, answering only what is asked of you, but also offering up any information that the officer needs to know about. Like, I recently had my van searched, and I told the officer that there's a paring knife inside the microwave, so don't go jammin' yer hands in there without looking.
When the opportunity presents itself, Canadian Customs will hassle a US driver just for the heck of it. US Customs will, too, but usually only US drivers.
If you deliver in Canada and then sit for a few days, then give up and deadhead back out, they know how long you were up there, and when you come out empty after a few days that's a red flag so don't be shocked if they want to do an inspection. I recently had a load to Edmonton, Alberta and broke down in Lethbridge, ended up taking nearly a week to get it fixed and back out to the States. While I was inside the USCBP building waiting for them to give the van a physical, there was a Canadian driver there putting a load of seed potatoes in bond, headed for Mexico. He mentioned that he was from Lethbridge, and I mentioned that I had spent a lovely 5 days at the ThriftLodge there in beautiful downtown Lethbridge while my van was being repaired. The US Border guard overhead this (which was my intent) and he commented, "Oh, that explains it." And it turned what could have been a lenghty wait for a thorough inspection into a 5 minute deal.
Canadian Customs has a list of resricted and prohibited weapons at
bsf5056 I Declare
There are many items listed, tire thumpers, hammers, screw drivers and backscratchers (hey, you can put an eye out with that thing!) not among them. The last item on the Prohibited Devices list is,
devices prohibited by regulations, meaning any item specifically prohibited by the Canada Criminal Code as being specifically designed as a weapon as its primary purpose.
So again, a tire thumper under the front seat of a car will be suspect, as a four-wheeled vehicle's need for a tire thumper is highly suspect, but a tire thumper under the front seat of a truck could only be considered a weapon if you are engaging in some other illegal activity, as the CSBA cannot just arbitrarily define something as a 'weapon by design' unless it is also defined as a 'weapon by design' in the Canada Criminal Code.