i have an idea...
get something like this
not the cheapest, of course, but imagine using the bottom cabinet, insulating it, and shoving a doorless mini fridge into it, kinda like what alot of guys here do for their ferm chambers, kinda like this example
maybe going overkill, but if you can meld those 2 projects, I think you have a winner. granted, im probably just telling you what you had already wanted to do.