You can do all you suggest but it will be 10x harder than going with a conventional setup (touchscreen) and just disguising it in some way. I saw a bmw pic around where the owner had an LCD low in the dash and when he left his car he had a notepad (pad of paper) he would put there. The notepad looked “installed” so nobody would expect to see anything behind it. That is what I am talking about. A fake cover for your LCD or something that makes it look like your stock faceplate. Anything like that will be way easier (and just as effective) than trying to wire everything to your stock components.