Hello danijelb, and welcome to the forums.
Your prototype unit looks pretty good.
I would only note that the firebox seems quite over-sized but that is not a problem.
It would also perform better without the horizontal run and 90° elbow in the exhaust.
Your commercial unit raises some questions.
Are you planning to use tuning plates, or reverse flow, or hybrid?
If going reverse flow, your door cutout appears to extend past the end of the RF plate unless you plan to add a domed end.
Generally you want to have the racks over the RF Plate so that drippings do not fall to the bottom of the smoker where it is harder to clean.
If your RF plate is removable it will not matter as much.
I also note that your FB-CC opening is not the best shape, and it appears to be too high.
I am assuming based on the curved top of the cutout that you are planning to use a round firebox.
Whether going with RF or conventional tuning plates, it is best to have the top of the FB-CC opening be even with the RF/Tuning plates. The bottom of the cutout should follow the contour of the bottom of the CC.
The shape of your cutout with the faceted bottom will create more turbulence and restrict flow.
You may want to post a drawing of your design with dimensions so we can better evaluate any other potential issues before you get too far along.
I hope this helps.