Thanks for the responses, guys. I got a Commercial 4000 humidor by Quality Importers. Here's what it looks like:
https://yourelegantbar.com/products/...abinet-humidor
Bob says I would need to put like 2" of insulation all around the entire inside.
Adam, I don't live in NorCal anymore (no more perfect weather).
I live in Lancaster, which is REALLY hot in the summertime (over 100* from May through August, basically).
I've already put rubber insulating tape around the doors. Getting the humidity dialed in has been a chore. In fact, I can't even keep the humidifier in the lower left corner as it is designed for. The top shelves just won't come up. So I'm keeping the humidifier (HUMI-CARE XG1000) on the lower middle shelf. I've got 2 old school Oust fans running and also a very overpriced humidor fan (Xikar Purotemp Humifan Air Circulator).
The cabinet SEEMS to hold humidity somewhat well with the doors rubber taped, but the humidifier starts straining after about a week, and there's quite a bit of fluctuation in the humidity depending on room temperature and the area of the cabinet. This wouldn't be a problem, but since I travel for work anywhere from 2 to 7 weeks at a time...