Highly recommend the drip bucket liners. I’ve had raccoons raid my drip bucket when I didn’t clean it out soon enough and those liners make for easy cleanup.
As for the bottom of the smoker, you’ll end up with some grease that doesn’t make its way to the bucket, so every so often I take plastic putty knifes that you get for painting and scoop out any excess grease.
I have something similar in our house. It’s hiding the hvac duct because of a load bearing beam blocking the duct from running in a perfectly straight line.