Originally Posted by
persianpower
The other issue is I have a lot of shampoo, toothpaste, electronics, and other items usually barred from carry-on baggage. I don't want to lose these items, so I feel inclined to hide them deep in my carry-on bag. It's a large camper's backpack. An item usually checked in as luggage but in my case, that's simply not an option.
That's a whole other question.
It's likely these items will be detected and confiscated. The rules are here:
http://www.catsa-acsta.gc.ca/english/index.shtml
The X-Ray machines can 'see' deep into bags, and if they can't see what's in there, they'll make you open the bag anway, and and throw things away.
Also, Transat is generally fairly strict in enforcing its carry-on policy. Make sure your "large camper's backpack" does not exceed 22 pounds, and isn't bigger than 9 x 16 x 20 inches, otherwise they'll put it in the hold. The rules are here (scroll down to the grid):
http://www.airtransat.ca/en/4_6_1.asp
Frankly, for the $50 the change fee will cost you it sounds like you should just bite the bullet and pay it - A lot less hassle in the long run.