Opinion 1: if you are at a steady 68 degrees, then go with either a door OR a gate (whatever you prefer). I do not think it can matter too much either way (with respect to the longevity care of your wine).
Opinion 2: ITS WAAAAAY TOO SMALL!!!! (don't take this to heart. I am one of those sick folks out there that feels no basement is large enough)
LOL that space actually runs about 28' in length but it would be awkward that big. I may extend it to 10' though.