I'm going to come in here and open my mouth...
First off what state are you located in, sometimes someone on here local will offer to give a hand. If you were in Florida, I'd help you out.
Secondly... I am a "retired" Ford Master Technician. While I worked for Ford, I had a lot of pride in the company, even though I thought about 97.8% of the "technicians" were parts changers only. While I worked there, I got mad when people knocked the dealers. But now I see how things really were.
That said... I wouldn't trust a DAMN thing a dealer tells you. They have a reputation and a stigma that, "well, they built my car, I know they can fix it!". That's bologna though, so many times I saw vehicles mis diagnosed. Engines/transmission assemblies, when it was something minor and inexpensive. What if you let them perform $2200 worth of work and the problem is still there? The tech panics, finds out it was a $5 sensor puts it on the car and doesn't tell you. Or the next thing they want to throw at it is a PCM, I'd put money on it. You need to find those hole in the wall places that you can trust, and its usually best to get a second opinion AND ask them what happens if their repair doesn't fix the problem, before you give them the OK. That way, they know you aren't paying for what doesn't fix the car. ALSO, the latest Ford scan tool doesn't give any kind of print out, that's bull. It's a laptop, and in all my years, I never printed anything, and Diesels especially were watched like hawks by the Ford Warranty department. (They can, but its not general practice. we printed things like info from the Ford website). This sounds like a dumb Ford tech throwing the most expensive stuff at your car, right off the bat.
I'm sorry for my rant, but I worked at 3 Ford dealers and while not every tech was bad, most were.
Look around at salvage yards for parts, especially something like cats. IF you had a actual problem with your cats, I would probably just get them deleted. And, I don't recommend it personally, but you could punch them out if that was your only option.
Lastly, what these guys are getting at with the O2 sensors, if I understand correctly, is remove the sensor so that the restriction in the cat will allow the exhaust to blow out the O2 hole. That will become the path of least resistance.
I apologize for the rant, but I also hope this was helpful...