If you dont have a plug for trailer lights already just go get one from the parts store, it T's in plug and play to your harness in the back and they have a dual set for slide in camper/trailor. They come with a color coded diagram for stop/tail/turn and the lights will reference the same. Remember you are adding to your existing so fuse size,relay.flasher will need a bump up. If you use LED they sometimes freak flashers out because they cant sence the lower amps but if you are tied in should be good. Then just run the wires from the T to the front of the bed... now here is your choice. Come up between the bed and cab and feed the wires into the rack or up from the bottom of the bed. Either way internaly the rack cant be blocked as you have to fish the wires up in one go with the ends all as one taped up. You will have all your light holes drilled so you can work it along easy once you get topside. I would say make the wires 6' from where it comes to the top of the bed and then travels over to your opposite side. If you are not up to snuff grab a small spool of the colors that come with the plug. (yellow,green,brown,white) and that takes the guess work out at termination. If you are putting over head lights up top include one red (pos+) for each light and a big fatty ground they can share and they get pulled up with the same harness but those will run forward eventually to key on, Switch, batt and relays. You can stub them bottom side and hook up later if you choose. On another note round lights are easy peasy with a hole saw and if you use diamond plate that may disrupt your seals but even so think about water drainage. 3rd brake light with cargo light is a thought also. Good luck and times.
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