re: Ganache

Thanx. I have a recipe for ganache filling and frosting.
The filling for dark chocolate is 1:1 with 2tbsp butter,
The frosting is 2:1 with 2 tbsp butter.
For white chocolate filling is 1:2 and for frosting it’s 1:3.
Does that sound right.
I just wanted to know if with the 1:1 ratio will it be ok to store the cake outside.