Not considering the weight or brakes, a 5th wheel connection has advantages.
It make the rigmore stable when towing due to less of a tendency to sway.
You get better weight distribution with the tongueload between axles.
It also makes it easier to maneuver in tight spaces and it's way easier to back up.

 

I do it with a 30' ultra light travel trailer and a 1/2 ton with 5.9L. Weight on trailer loaded is around 7000 lbs. and it has a fairly heavy tongue weight loaded close to 1000 lbs. Use weight distribution hitch and anti sway control. I put on super springs (great product) and did change to 4.10 gears helps alot on the hills and actually improved towing mileage slightly. I would not tow my rig up and down alot of steep mountain grades. It does it and stays ahead of truck traffic but I just don't like putting that much constant strain on the truck. On flat ground it is great. With a fifth wheel you will really want to pay attention to the pin weight. I am definitely pushing the weight limits on my truck. My truck is a 1999 with hypertech (mainly to get rid of death flash), 265/75-16 tires, 3" single magnaflow exhaust and drop in trueflow air filter (recent change).

 

Vsrapter, you will have no problem towing 6500lb. or less trailer. Check out the site big truck guy gave you and go to your a few local RV centers and check out 5thwheel hitches, also check out any place that just installs trailer hitches and see what they have to offer like, Reese......etc.
Happy Towing