Comment by mindslight

Seconded. I've used those exact cartridges. Not for as long of shifts as you, but I'd say the face mask fit is much more important for that.

My DIY-perspective tip is that when you're getting to know the respirator, you can take the filter cartridges off and put your hands over the input ports to feel what fully restricted breathing feels like, make it a known sensation in case it ends up happening. Likewise you can cover the output port and breathe out to do a kind of rough fit test.