When I mention a screen top cover that I used, you can certainly use your regular inner hive cover. I would put a 1/8" size piece of hardware cloth over the hole and put the jar feeder on top. This allows you to feed and not get bees into your space. My workshop is in the 60's during the day and 40's at night. The bees all seem to be doing well. I have certainly enjoyed the hive smell and the buzz as I work in my shop--but, it is getting pretty crowded in there.
Let me know if you have questions or suggestions. Remember - this is an EXPERIMENT that will hopefully give us another tool in our North Country Beekeeping "bag of tricks".