Welcome to the forums!
I like the idea you have and I'm not sure if there is a good way to do this.
I've attached a block that works for what you want but there might be a better way to perform this task. I know my block doesn't use the same justification that you mentioned, but it still serves its purpose.
With this block, only edit the "Contents" attribute, and then regenerate your drawing, and the text within both visibility states will update.
Hope this helps!
