Canadian Tire here has a smal RV parts section. They have a trash can that mounts on a cupboard door. Similar to ones built for homes , but smaller for RV use. I have looked at them , but they won't fit the trailer and would be in the way in the camper, so we just use a waste basket and like others take the trash to the bin on a nightly walk.
CTC should be able to order one from the catalog if they don't have them in your local store. Of course an online search of the catalog showed nothing.
Good luck in your quest.