Mixing condensed and evaporated milk for fudge?
This is the label information from the reduced sugar sweetened condensed milk made by Nestlé:



That suggests to me that there is more to creating a lower sugar sweetened condensed milk than simply reducing the sugar. I have made sweetened condensed milk from evaporated milk (goat's milk actually), and I found the experience a bit more advanced than simply slowly stirring simmering milk, and the sugar seemed very crucial to the operation. Cajeta with powdered goat&#39;s milk? Or evaporated? (Experiment Results)

For comparison sake I looked at the ingredient list for regular Nestlé sweetened condensed milk (La Lechera). The ingredients of that product are milk and sugar.

I won't go so far as to say that it can't be done as you hope, nor will I say that the fudge wouldn't be tasty, but I have serious doubts.