I have flown inter-Canadian from airports smaller than Thunder Bay (never been to Thunder Bay though). The one thing I would advise is to follow the letter of the law, do not try to leave the liquid bag inside a carry-on. My boss is one of those "oh, they don't care about the liquid bags" people. He got the whole nine yards at an airport smaller than Thunder Bay, bags entirely unpacked for everyone to see, etc. The people treated him like they found bin laden himself.

The one thing the TSA does have over CATSA is that they construct the checkpoints better. The key is to have lots of rollers leading up to the mouth of the x-ray. Many Canadian airports, domestic or to the US, do not have lengthy ones, so the line slows to a crawl.

CATSA does HORRIBLE staffing at checkpoints. For example, in the US, the TSAer at the magnetometer will shuffle you off to another TSA if you alarm. With CATSA, that same person gives you the patdown and waving of the hand-held device. All the time, nobody can go through because the person is not watching the metal detector. I have been in lines with two or three people ahead of me and it has taken five to 10 minutes to go through from that point.

Be prepared for an inordinate amount of BP inspections (none with ID). For example, in Toronto T1, you get a total of five inspections BEFORE clearing the checkpoint (1. Entering Customs Hall, 2. US CBP stamping your BP, 3. CATSA person in the middle of the line with one of those electronic guns scanning your pass, 4. The person at the randomizer (the green arrow thing), 5. The person at the mouth of the x-ray). Then you have to show your Passport and BP again at the departure gate as you board.

When you fly domestic, it will be two checks. Someone at the end of the roped lines and the x-ray bin feeder.

I've been told that CATSA Toronto has a very high turnover rate of people, few are pleasant. Most have the facial expression and body language that they would rather have a root canal.

Good luck.