I like 5th wheel trailers. I owned a 30-foot gooseneck trailer and crew-cab dually myself.
But towing a 5th wheel is best accomplished with an 8-foot bed. Anything less produces a situation where the cab can hit the trailer in tight turns (such as campsites, u-turns, etc.) This is worse if the pinbox does not jut forward. Your straight-pin trailer is fine for an 8-foot bed, but is less ideal for a 6.5 foot bed.
When towing, the 5th-wheel pivot point needs to be mounted directly over the rear axle (1 inch forward, sometimes. Never behind.) In an 8-foot bed, that puts the pivot about 4 feet behind the cab. Trailers are usually 8 feet wide. No problemo.
But a 6.5 foot bed has the same rear overhang from axle to rear bumper, so the cab is 1.5 feet closer to the pivot. The pivot-to-cab distance is down to 2.5 feet--something that limits your safe turn angle.
A 6.5 foot bed can be made work if you install a Reese sliding 5th-wheel hitch, or equivalent. http://www.campingworld.com/browse/skus
This one allows the pin to be over the axle when towing, but allows a lever to be pulled (while stopped) before tight maneuvers to allow the pivot to slide 9 inches back. This still doesn't allow a full 90-degree turn, but it increases the distance to over 3-feet and increases the angle of turn enough for campsite maneuvering. I've towed with one on a 6.5-foot bed and it does OK. Add a jutting pinbox and you get even more turn clearance.
But the CrewMax has a stubby 5.5-foot bed. I don't think you can get enough cab clearance for regular turning in normal driving, when the pin must remain in the forward position over the axle. A jutting pin combined with a sliding hitch is your only option, I'm afraid. Even then, a 5.5-foot bed might not be enough.
Grab a tape measure and see how much distance there is between the axle centerline and the cab. If you draw it out, with the pin setback of your straight hitch included, I'm sure you'll see how limited your turn angle would be.