My club has a walk in that is much larger than what you are needing. Ours is an insulated truck body with the fram removed. Works like a charm even after sitting up for 10 months. We have to service it about every two years. It will hold 32 deer I recall. We have a rail down each side, and hooks that go over the rail and hold the deer by its pelvic bone. I expect the body is 30 years old.
We keep the temp around 40 degrees. Has a high and low setting. Runs on 120v. I like to hang a deer for a few days before deboning it for burger. If the deer will be used for chops and roast, two weeks of hang time is about right. Been my experience that well aged venison gets mushy when put through a grinder, so I don't age deer more than a few days that are going to be ground