Check with those tech's making sure that they installed the high speed 5th wheel hitch and the corresponding 100 MPH pin box on the trailer. Other wise you will be in real trouble. Normally you really have to probe the techs for them to come clean and tell you about existence of these special parts for high speed towing. Without them the king pin can go into oscillations on three planes.
If the techs just play dumb with you, then call Summit Racing at 1-800-230-3030. They have an adapter that installs between the hitch in the truck and the pin box that is only $146.99 and ships free as it is over a hundred bucks.
The Summit part numbers are as follows:
Ford FOOl-001
Chevy FOOl-002
RAM FOOl-003
Chris