Just as some people espouse, Ford, Ram, GM are total junk. Don't know how they stay in business. Over the last 40 years that I have owned them, I have had major problems once a week. Jap stuff, on the other hand never has problems, never has a recall and I wonder why they even have warranties and service centers. All they need is an oil change rack.
On to reality, if you go ahead with the diesel, when you get ready to get your next 5er, it won't even be a factor. Diesels, IMO, don't pull a bit better than gas, they pull much better. I have owned two diesels, put over 100,000 towing miles combined, and still haven't realized these massive repair bills people keep telling me I am getting. Guess I'm missing something there.