Learning generally boils down to "Repetition or the avoidance of pain", some people learn by doing, some by watching and some just have to pee on the electric fence.
Whether you think that you can, or that you can't, you are usually right. Henry Ford
Afraid I’ve got little advice to offer as I’ve no experience with a vertical smoker. Guess I would make the throat adjustable tho to give you some wiggle room.
How are you doing shelves in that...or is everything going to hang?
I think we need some more information or a sketch of your idea.
Welcome. My advice is do what dirtytires suggested and get it up and running before any paint and see if it works, see if it holds temp, see if it gets hot enough.......run it and make adjustments from there. I would make a baffle that has smaller openings on one side like a tuner plate and place it above the fire box opening inside the cook chamber and put the smaller openings toward the fire. Make it removable. You may end up redoing the firebox or you may nail it right off the bat.
If you can control your fire via air inlets, you shouldn’t have to use baffles to keep the temp under control.
Did you build an offset firebox, or did you set the lighthouse on top of the firebox?
Or was it an integral part of the lighthouse?
Any pics of the completed project?
And most importantly, how does she cook?