[markem]

You have a small walkin that will have a door and nothing inside is visible from the outside, right?

I'd do wrap around open shelves above the open wine boxes. For singles, I'd get a couple regular humidors and store them on the shelves. Make sure that the shelves are deep enough so you can leave an air gap in the back (don't have the boxes touch the walls). This will aid in circulation.

I'd probably also put a couple small fans on the floor, pointed up at an angle. This will help to reduce dead zones where mold can form.

Keep it simple, especially for now. You can add fancy stuff later.