1) Do you need the truck all the time for work? If not, a car getting 30-40mpg makes more sense.
2) If you do need a truck, you are probably can justify diesel from an MPG point of view. That's north of 60,000miles per year with 17,000 towing.
As far as 3/4, 1 ton, dually...what size 5th wheel are you looking for and how old of a truck are you looking to buy? Particularly newer 3/4 ton trucks can pull pretty big 5th wheels. Since you know you are looking at 5th wheels, now is the time to check them out and decide how big you will go. A blanket...you need a dually...is false.
