It seems towing and hauling is where diesels get the biggest mpg advantage, so IMHO if that is a small part of how you are going to use the truck gasoline may be a good choice.

On the one hand you often get most of the cost of the diesel upgrade upon resale, but on the other hand diesel emission requirements seem to have reduced their fuel efficiency and made repairs more costly.

I haven't really heard anything bad about the gas engines of any of the big 3.

 

I'm only towing when taking 5er out with the family. This is my yearly itinerary for the next few years.....

One 4 day trip in Nov less than 700 miles round trip
One 7 day trip in Dec " " " " " "
One 4 day trip Feb. " " " " " "
One 4 day trip in April " " " " " "
one 14 day trip in July about a 5000 mile round trip
(CA to FL, CA to MA, CA to ?)

Based on this, is a gas more reasonable considering emissions, price of diesel, cost to repair, etc?

When not towing, it will be my daily driver. Currently 16 miles round trip to work.
Possibly, in a future job, I would not work further than 90 miles round trip from home.

 

Wow I wish I got to take that many trips. Diesel would be my choice, but I do my commuting by motorcycle most of the year.

Towing up to an ATV park I got to chatting with the neighbor. His slide in camper and trailer were probably similar weight and wind resistance to the 5th wheel I had.

I got about 12 mpg towing up the mountain. He told me he got 6 point something with his gas truck.

To me, that would be kind of hard to take.

 

Gas will do the job. Make sure it has a big fuel tank. I had a gas Chevy that I needed to fill twice in 5 days and I got tired of stopping all the time.

Normally, I would choose diesel every time. But modern diesels are choked with emission requirements and too many parts and pieces and do not deliver economy or reliability like their simple reliable ancestors did.

I went from a 12 valve to a high dollar CR truck with all the goodies. I sold that truck due to costs of ownership and have a new low miles 12 valve that I'm making like new inside and out to fit my needs. I like the old fashioned simplicity, economy, and reliability of the 12 valve and Dodge. I will add stereo / nav and custom interior to make it like a newer truck and mod the driveline for towing.

 

Yeah I searched long and hard to find an 06 Laramie dually stick, to have the last of the 5.9's with less emission stuff.

Remember when gas first started to get emission stuff? Cat converters would plug, early fuel injection didn't run well, smog pumps would fail...

Now gas engines, with all their emission stuff, run better and are more reliable and get better fuel economy.

Hopefully diesels follow the same path.