As tempting as it is to sneak herps in to the country, mainly to avoid dealing with Customs agents' ignorance, I wouldn't recommend it
If they are not CITES listed animals, make sure to bring along documentation/info regarding the animals you'd be importing. A simple picture of the animal and some basic information will do.
Have your receipt ready as well.
I'd also suggest you crossing back into Canada before 3pm. This is so that if you do run into a real arrogant agent, that won't let you back in with that animal regardless of all the info you've provided them, that you could tell them to call Environment Canada to confirm it. And whatever they hear from them is what goes.
Sometimes you luck out where you don't have to deal with this nonsense, and sometimes you gotta deal with it.
Just don't lose your cool...lol or tell them how to do their job, like I did once. lol.
Other than that you should be fine.
There's no need to book for an inspection / or get a health certificate to bring them back into Canada if not CITES listed.
-Sam