Has anyone tried this? Due to the extremely hot and humid weather in our country, ganache still tends to soften under fondant, and I lose sharp corners or the fondant just melts along with it. 

I'm thinking of straight up swapping the cream for condensed milk in the ganache, thereby producing a fudge --just like in a 2 ingredient fudge bar recipe.

Since fudge bars can stay stiff at room temperature AND through the humidity here, I was thinking of spreading the mixture onto cake in place of ganache. I just want to get the stability everyone gets with ganache, without the fear of melting /softening in the heat and humidity.

Any thoughts? 

I am no help asni never tried but let me know if it works please. 

I make a fudge filling but feel it isn't spreadable as nicely once set. It's a different recipe than yours so don't know if it would behave the same way...

I've never tried it either but I love your problem solving thought process -- but I have made fudge pieces in silicone molds and love the results -- it does hold impressions well -- yes please update on your progress -- best to you