[Wally15]

I've been following this thread for a month now. Some very interesting and informative feedback. Five years ago I was going through a very similar vehicle situation and decision-making process as the OP; frequent short "daily commutes" and several long (up to 3K miles) trips per year requiring more truck than my '04 Silverado 5.3 gasser could comfortably handle. At the time, it wasn't an RV towing issue, it was an 8K lb boat and trailer that was straining the gasser. I had never owned a diesel, and in '09 most of the new diesels were still having problems with the pollution control mandates. Plus new diesels were very expensive, and retirement was just around the corner for me. Didn't want a lot of new debt.
I had no particular brand loyalty, my Silverado I purchased new because it was the most comfortable to drive, and I liked the ride and interior amenities. Biggest thing I towed back then was a bass boat. I test drove all the Big 3 diesels and liked them all, except for the price tags and trade-in. Each had pros and cons over the other two, I'm in basic agreement with all the previous comments. One thing I didn't like was the lack of "maintenance history" on the upsized engine displacements. I would have probably bought the Ford if I went the new vehicle route.
I ran a couple of spreadsheets on a new "double duty" truck vs buying a used pre-07 (EPA) diesel and also a 2nd car for daily commutes. Out to 6 years of ownership, it made more economic sense for me to buy 2 used vehicles than one new truck. I ended up purchasing an '06 2500 Ram Laramie Cummins and an '02 Toyota Avalon, both with less than 100K and both with excellent service histories. And sold my Silverado privately for almost as much as my trade in allowance would have been. I decided on the Dodge because of the Cummins. IMO Dodge is the least "comfortable" of the Big 3 interiors, but the reliability and low end power of the Cummins is a nice offset. I have put slightly over 60K on each vehicle over 5 years and (other than scheduled maintenance) have only replaced an O2 sensor on the Avalon, and replaced the xmn solenoids on the Dodge 48RE tranny. And I purchased both vehicles for almost $20K less than I would have spent on one new diesel.
Per my spreadsheet, I'm saving $1,300 per year owning 2 used vehicles as opposed to one NEW double duty diesel. New vehicle depreciation is the sole reason for the savings.
Since the OP will probably upgrade to a Class A as some point in the future, I think looking at 2 used vehicles has merit and should be factored into his decision. And as the price difference between diesel and gas continues to spread, my savings actually increase.

And last year when we decided to become RV'ers, we based our purchase on what the Ram could comfortably pull, so we ended up with a 9K max weight Laredo 308 RE TT, and use the covered and lockable truck bed for much needed additional storage. Plenty of room for two "empty nesters".
I have decided to keep the '06 Dodge diesel for the foreseeable future. By spreading out my annual mileage across 2 vehicles, it might last me another 10 years or so. Or until I'm too old to haul the TT or boat safely. In any case, I probably won't ever buy a new vehicle again. Unless I win the lottery.
Notice I didn't comment on the cold weather operation. Not generally an issue for me down here in S. GA. However, last week it was in the low 20's, which is unheard of before January, much less Thanksgiving. No wonder they renamed Global Warming to Climate Change.