I have been in trucks with the newer diesel engines and they aren't that loud, heck, almost too quiet for diesel.
I am really looking at a 2017 Thor Miramar 35.2 (love the floorplan). Selling price $119k. If it had the 6.7 diesel from Ford, I would see it as a $139k RV and for the additional monthly payment cost of maybe $20-$30, I would jump on it.
BUt, it seems that when you put a diesel in ANYTHING they then upgrade EVERYTHING. Just like when I was looking at my current 2008 Kodiak chasis...Gas V-8 was $40k cheaper because all the ones with a diesel went with full leather interior, upgraded cabinets, etc, etc.
Maybe the V-10 is just that good where people are perfectly happy with it and dotn feel the need for the additional power of a diesel. I just don't like the RPM it runs at and the constant downshifting to stay in the powerband.