I use the wilton base recipe for my buttercream but use 75% butter and 25% shortening to help with hotter temps and melting.

My business has grown and I am short on fridge space. I cannot fit another fridge into my space to store completed cakes. I have always iced thursday and then refrigerated the cakes until Saturday delivery as I added decorations friday etc. 

I am now stuck as I am out of fridge space for refrigeration. So this is a 2 part question:

1) How long can I leave the Wilson BC icing out for (I used water instead of milk) with most of it being butter? Do I have to fridge it that whole 48 and possibly 72 hours before delivery?

2) Does anyone use all shortening Wilson BC recipe with no butter and no dairy so the icing can be left out for however long?

Thanks!

You can leave your cakes UNfrig'd for 3 days but be aware that means the customer will have that much less time to consume any leftovers.  Oh, it also matters if your location is high humidity - of course that will cut the time down.  You do not need to go all shortening and/or no milk.  It makes little difference as the amount of sugar in the recipe sort of nulifies the problems.    I delivered 100s of cakes w/o any pryor  refrigeration so NO you do not need to frig it at all but......that said, it does help keep the cake a bit more stable if it is cold - even if only frig'd  overnight.

Though I only do cakes for fun I have never let a cake sit for 3 days before giving to someone. I have had a cake that I made for my home sitting for 3 days while eating on it. By 3rd day all of cake was gone. I had it underneath a glass dome cake plate. I always tell people I give cake to to place sedan wrap over the part of cake that has been cut because it keeps a cake fresher for longer but normally the people I made for eat it within 2 days and it is gone.