If the bed is pre-wired they should have a ground wire in their loom... I'd run it to the frame... I'd also run a second ground, at least 12 gauge to the engine compartment and tag one of the grounds that the factory uses there....
I know that one some of the trucks you need a resister across the turn signals to make them flash at the correct speed...
I have a flat bed on my 05, I used to run a small fleet of 4-5 trucks... I don't use LED's... we had a flat bed rear ended in the winter during a snow storm... the snow covered the lights... and than it was hit... we took out and removed all the LED's and moved back to the sealed 4" units.... there's enough heat with the tail lights running during the day to keep them melted off...
On all our trailers we used the wiring for the trailer plug to power relays on the trailer for the lights... we ran a 10 gauge wire to the trucks connector, and than through the plug to the battery on the trailer... we installed a box on the trailer and put a relay for the tail, turn, backup lights... the only circuit not on a relay is the trailer brakes... this keeps the load low on the truck wiring... geez those are small wires....
there's nothing at the back of the truck that I know you can hurt with a poor ground except for a circuit not lighting correctly...
We found some 1/4" thick rubber we used as a cushion-er between the bed and the frame... we actually added some brackets and fasteners to keep our beds secure to the frame...
I know that one some of the trucks you need a resister across the turn signals to make them flash at the correct speed...
I have a flat bed on my 05, I used to run a small fleet of 4-5 trucks... I don't use LED's... we had a flat bed rear ended in the winter during a snow storm... the snow covered the lights... and than it was hit... we took out and removed all the LED's and moved back to the sealed 4" units.... there's enough heat with the tail lights running during the day to keep them melted off...
On all our trailers we used the wiring for the trailer plug to power relays on the trailer for the lights... we ran a 10 gauge wire to the trucks connector, and than through the plug to the battery on the trailer... we installed a box on the trailer and put a relay for the tail, turn, backup lights... the only circuit not on a relay is the trailer brakes... this keeps the load low on the truck wiring... geez those are small wires....
there's nothing at the back of the truck that I know you can hurt with a poor ground except for a circuit not lighting correctly...
We found some 1/4" thick rubber we used as a cushion-er between the bed and the frame... we actually added some brackets and fasteners to keep our beds secure to the frame...