In my experience there is nothing better than ganache (i use 3:1 choc:water )under fondant to give a perfect finish. Especially if I’m working on something for a couple of days. I think ganache would be best. When it comes to using cream cheese, in Australia the food safety rule for perishables is. Once it has been out of the fridge for a couple of hours it should be consumed or thrown out. I think if I had a project that was going To take a few days I would probably steer the customer away from cream cheese. Hope this helps..