I'm sorry you are having this issue, but thank you for trying to figure out how to solve the problem and not just dumping him in some shelter.
You have some great suggestions. Since you seem to have covered most of the bases, hopefully going the medicated route will work. Feliway is certainly something you should try. As Chico mentioned, it's been working very well for her. Also, I'm all for medication. I had my Czari on prozac for about 6 months while trying to integrate her and I found the easiest thing to do is either get a pill pocket, or I found Pounce treats work well too. They have some moist ones you can mash together and put the pill in there and they also have a little pillow type one, I used to slide the pill in there. Czari never knew she was having a pill.
I wish you the utmost luck. Ford should be spending his senior years with his family.