If I wanted to open a Canadian restaurant in, say, Dallas, Texas, what would I have on the menu?
Poutine.
That’s the only thing I could think of…
There is a Wikipedia article on Canadian cuisine (ETA: just mentioned by Winnipeg). A lot of the things mentioned there seem derived from other cultures, but there is the Jiggs dinner which seems original.
Don’t forget seal flipper pie and Nanaimo bars (a mari usque ad mare).
Bacon
Things flavoured with maple.
I ended up in a Canadian restaurant in Paris. They served pub food and had a hockey game on.
Here’s menus from a couple of (very tasty) Quebec restaurants that have a Canada theme. Conclusion: Frenchy, plus a lot of wild game/seafood.
http://www.auxancienscanadiens.qc.ca/menu.php
http://www.beaverclub.ca/
Moving away from the haute end, yeah, beyond poutine and maybe smoked meat sandwiches (mmm), you might struggle a bit to find much distinct (or at least marketable) – see how Disney fared with the attempt at Epcot (answer – not all that well):
Variations on Nanaimo bars (I like the irish coffee one), both fresh water and ocean fish, Timmies (you’ll have to smuggle them), salt & vinegar chips, scotch broth, awesome steaks, delicious Belgian-style cakes and don’t forget the mac & cheese with cut-up hot dogs. 
Be sure your condiments include mayo and malt vinegar.
Per their website, there are Tim Hortons in Michigan, Maine, Connecticut, Ohio, West Virginia, Kentucky, Pennsylvania, Rhode Island, Massachusetts, and I can vouch that they’re all over New York City now.
that would be back bacon
Possibly peameal back bacon.
Butter tarts. Bannock (baked or fried). West Coast style smoked salmon(not like lox or Nova Scotia smoked salmon at all). Saskatoon berry pie. Blueberry grunt. Cod with scrunchions.
Grits? 
Only in South Canada.
Goin’ the Bob and Doug McKenzie route, I’d say back bacon, cigarettes, beer and crullers.
Humility.