A few years ago, for 2 years, a co-worker of mine provided essentially the same dynamics. Unfortunately, he had to tell me he couldn't do it anymore. Another co-worker agreed to take them the following year but his conditions were not good - too warm and dry. I lost ~half of the collection. I had a wholesale greenhouse take them last year and the plants did well. But the owner was worried about the responsibility and I decided that I wouldn't ask her again. Before all that, before we moved, we were living in a 2nd floor apartment that had an attic. That attic was ideal - cold, but not too cold, with windows.
I was hoping to get the Botanical Gardens to house them for the winter and ultimately that fell through. I brought the plants to the meeting, at the Botanical Gardens, before I got her last message, stating that she couldn't take them. After the meeting we talked some more about it and the conditions wouldn't have been all that good anyway - total darkness. She offered her garage and that wouldn't have worked either. However, one of the guys in the meeting volunteered to house them for the winter. So after the meeting he took them. He has a garage that will be ~refrigerator temps and windows. That's about right. I offered to augment his small collection of plants.