I always stabilize the egg when it is empty, no food, no plate setter, once I add those things the temperature goes down for a long time (an hour plus) but it does not go much above the stabilized temperature. I have no trouble with drying the meat and use no water pan. As far as beer can chicken in my experience you get a more even cook with a spatchcock chicken.
I think the biggest problem with temperature control is micro-managing. I stabilize before I add the plate setter and the meat, then when the meat goes on it will read low for an hour or more but is not an issue as it will come back up. Patience is a virtue especially for egger because temperature changes take a long time, when you change the vents now the results are probably not apparent for a half hour or so. So sit back and relax. And don't get to serious about an exact temperature, 225º is nice but 240º works just as well.
I think it looks like a great room but is it really a man cave if the swmbo designed it. I kind of like the old furniture in the garage where you can sit on the furniture without getting heck for having oil, grass or whatever on your clothes. Beer fridge and a dart board and you are getting fancy. Like I said looks like a great room and your wife has good taste but not a man cave if you have to act all civilized to use it.