Ferm Chamber Ideas: Top Freezer/Bottom Fridge

OK, so we are buying a new home and am turning a former 'photo darkroom' into my 'brew room' when we move in. I'm getting a Kenmore over/under fridge donated to me that I plan on using in the brew room. Now, I plan on putting it on the right side of the short back wall shown below:


What I'd really like to do is build a large fermentation cabinet to the left of the fridge and basically take up almost the whole back wall. I was thinking that I could cool the ferm chamber using a fan and a controller to exchange cool air from the fridge (or freezer). The fridge would be on all of the time as normal with only the fan cycling to maintain temps in the chamber. The more I think about it, the more I feel like it won't work and that it is too big of an area for a 'fridge' to handle and I'm not sure if the freezer would do it either.

I wanted to be able to fit a couple 15-gal demijohns in it and regular 5-6 gal carboys. So I was thinking one or two shelves inside of a 5' or 6' tall chamber thats 5'-6' wide and 24" to 30" deep. Anyone have any insight or tips?

Might want to check out this link: https://www.homebrewtalk.com/f51/i-give-up-124057/ before deciding on what you want to do. Personally, if I were doing this, I would at least go with a chest freezer. The OP in that other thread is using a freezer though, and he could not maintain proper temps in the chamber area connected to the freezer.

You may have better luck as you are inside though. I belive that his was housed in the garage and it could have been quite hot in there while he was doing his testing.