I need a filling that MUST be stable enough to be left out of the refrigerator for a couple of days (going in a sculpted, ganache & fondant covered cake).
The use of Bettercreme is out, & I would prefer to NOT using a coconut buttercream. Ideally this needs to be more whipped cream or custard like.
I'm guessing just about any custard or whipped type filling would need to be refrigerated. The only thing that I can think of that would be ok out of the fridge for long periods would be to use Jello cook and serve pudding or a homemade pie filling. I used these to make pies with at a restaurant for several years and the pies were shelf stable for up to about 8 hours, but we refrigerated them after that.
For my coconut filling I make a shorteing only buttercream and add coconut flavoring and chopped coconut. I know you are not really wanting to use a buttercream, but it may be your only choice if you dont want to refrigerate.
Hope you get a better answer, good luck!