Personally I just use the factory plug in the bumper. There should be plenty of harness from the trailer to reach it. In the past I spliced in and mounted a plug in the bed. I have since learned that anytime, no matter how good a job you do, in time you will have shorts, corrosion or something that screws with your lighting and brakes. Running the trailer harness right to the factory plug eliminates any extra cutting and splicing. I also run a Prodigy, works fine on all my elec brake trailers, two axle horse, two axle car, triple axle flatbed.