Chest Freezer Ferm Chamber Extension Question

I've been trying to decide the best way to accommodate some conicals without increasing my footprint in my garage. I'm currently using a 15 ft^3 chest freezer with an ebay temp controller which works great, but the freezer isn't tall enough to work with a conical.

Any thoughts on pros and cons of removing the lid and building an insulated box on top of the chest freezer to expand the height, and use a bank of small fans inside to circulate the air to keep a fairly uniform temperature? I would build access doors on the front of the insulated box.

It would work, but how would you get to the bottom dump valve and racking port? It seems like they would be too low for you to reach.

I was thinking extend the total height to about 5.5 - 6 ft and putting them up on stands, I think that would give enough clearance to access the dump valve and racking port without too much bending over.

I guess my main concern would be temperature stratification from the freezer to the box even with the fans. I guess I could always build it out and throw in some thermometers and see how it does.

Upright freezer?

No, chest freezer.

Think removing the chest freezer lid, then attaching a 3ft tall insulated box with doors built in over the freezer, and using a fan bank to keep the air moving and prevent to much temperature stratification.

In a closed space like that, you would like need a lot less fan than you'd think. One small fan to move the air from top to bottom would probably be sufficient enough. If you put too much airflow in there, the increase will tend to suck the temp from everything in and around it a lot faster. (Think whirlpooling while chilling wort, same concept, just with air). May not be a huge problem, but it will cause your freezer to cycle a lot more.