We’ve crossed in the summer with 2 – 30 pound tanks for summer cabin use and they never gave them second glance or asked about them.
Be aware that in my experience the Canadians are super anal about the tank expiration dates and won’t fill anything that’s out of proof. Around here they don’t even give the proof stamp a glance, but up there they look at every tank, every time, every place that I’ve had propane filled.
Grouse