Hey, glad to hear you're enjoying the game!
Some kind of "try it out" mode is something I had considered during development, Picross DS did something similar.
Honestly, it's something that is unlikely to be added. It would be quite a lot of work, and I'm putting all my effort in to Tiny Train Sim now.
If I ever do any kind of sequel then maybe it would make it in that.
Personally, if I get to a point in a puzzle where I need to rule out an option then I like to draw a line/cross and then draw over it multiple times before continuing. Then once I have ruled out that particular path of logic I will undo until I reach the point that I started "guessing" that will be essentially flashing (drawing then re-drawing). Hopefully that makes sense and is of some use.
This gif might make my method a little clearer:
