Where do I begin to even look to rent one?
Those of you that do how do you make it work, one day a week, several days a week?
You can start by doing a google search for "commercial kitchen" or "kitchen incubator" with your city/county/metro area/etc. Where are you located?
We rent a commercial kitchen in CA, since it is illegal to sell food made from your home kitchen here. We usually have hours at the kitchen twice a week, can be more or less depending on our sales volume.