I recently purchased a GE 5 cu ft chest freezer because I have space restrictions. I am able to place two 5G kegs and a 10lb CO2 bottle along with a 3G keg on the compressor shelf. It's a tight fit. If you can upgrade to the 7cu ft model, you might be able to accomplish your goal without building a collar. HD has a great price on the 7 cu ft model for $179, plus free shipping. http://www.homedepot.com/Appliances...splay?catalogId=10053&langId=-1&storeId=10051
Again because of space constrictions, I have actually started to ferment in 5g kegs with really good success and it has made the whole process a breeze. No lugging around those heavy carboys and transferring is a breeze along with clean up. Good luck.
Oh William, I am not bound to please thee with thy answer. I was merely trying to convey what a 5cu ft freezer can accommodate and give him an option, as I have, to use this size chest freezer as a fermentation chamber. There is more than one way to ferment beer, my friend.
Just gotta chime in and say the last 2 posts were amazing. On top of that, I'm getting a 7 cuft freezer this week for my birthday. Gunna use it for fermentation as I have a 19.7 cuft already built out as a keezer.