Hi, and welcome to the forum.
I agree totally with Festus and his recommendation on the amount of stuff you will carry. The hitch weight you quoted usually from the manufacture is low, almost too low to really being meaningful. I would use a 15% (on the low end) to 20% (on the upper end) for the pin weight of the fiver. I would add the shipping weight + the carrying capacity weight, then mulipty by 15% to 20% to find the pin weight. Take a Laredo 310RE, this would be 13,000 LBS total, then you would either see 1950 Lbs or a max of 2600 LBS on the rear axle from the pin weight. Add to this the hitch weight, fuel, DW and what ever else you carry in the truck such as tools, snacks and the like. This could be over the recommend GCVW and axle weights of the 3/4 ton truck.
I know you stated your preference for a Chevy/GMC pick-up truck, but look at this web site.
http://www.dodge.com/bodybuilder/year.pdf
What I want you to review is the techinal section. In this section the Dodge Body builders web site provides informatiom on towing a 5er and or a TT. A 1 ton diesel with 4:10 gears and a single wheel model year 2010 will tow a 16,800 LBS trailer with a GCVW of 24,000 LBS. So I would be looking at a 1 ton signal wheel truck if available.
Jim W.
Jim