Quick reply because I've got twenty minutes of work time left then I'm going to roll into bed!

Personally I would say that a big backpack is a mundane enough piece of equipment to be bundled in with a concept of tinker, and have the animal companion be the bonus aspect. The backpack full of tinkering stuff could be like a knight's sword - it's a given that knight's have a sword, and thinkers gonna tinker, so you get tinkering stuff. If the backpack was filled with stuff not related to the concept (like a bag of... um, fish?) then it'd make sense as a bonus aspect because "tinker" doesn't often bring to mind images of someone carrying a backpack full of salmon.

Unless the concept is "bear tinkerer", maybe.

I may need to come back tomorrow morning and provide a better reply!