Grounding Issue for guide lights

[mjs5128]

Alrighty Folks, quick question for yas. I installed my VeVe guides the other day with the Smith guide lights mounted on top. During this time, I also changed out all of the lights on the rear of the trailer to LEDs (Tail lights, Strip light). All connections were made with with waterproof butt connectors. I tested all of the LED lights before I connected the guide lights and everything worked perfectly. I followed the install directions for the guide lights and connected the ground to the trailer (galvanized) using a small screw supplied with the lights. But, on my road test my guides were flickering when the trailer bounced. I'm assuming the trailer is making ground through the ball hitch to give me this result. Has anyone else had this issue? Would it be easier for me to just tap into the ground for all the rear trailer lights? If not, where the hell is the trailer ground for these trailers. I followed the ground behind the brake cylinder, but can't see where it ends up. I could run my own dedicated ground wires for each guide light to the front of the trailer and tap into that. Any ideas/input are welcome!

Could it be as simple as just connecting the ground using a bolt/nut rather than a small screw?

 

[WREKS]

If the trailer lights are working, I would tap into the ground there. I used 1/4" stainless.