I have a 7.1 cubic foot freezer that will hold four kegs: three on the bottom, plus on on the compressor hump. The 2 x 8 collar allows enough vertical clearance for the keg on the compressor hump.
The wooden collar is easy to drill for taps and gas lines. I have a six-port CO2 manifold on the outside of the collar with four gas lines penetrating the collar so I can turn CO2 on and off to each keg without moving the stuff stored on top (any horizontal surface is fair game for storage in my house). The fifth gas line has a gas disconnect for flushing kegs, pushing cleaner, sanitizer, and beer from one keg to another. the sixth gas line is for some yet-to-be-determined purpose such as flushing air out of the mash tun for low O2 brewing - maybe.
A 5.1 cubic foot freezer works well as a fermentation chamber with no collar. It holds either my SS Brewbucket or a keg - with no collar.
Both freezers were from Lowes, with their 10% military retiree discount. Both are controlled with an STC-1000 controller.