Since he hooked to another trailer, "I even unhooked from the trailer & hooked up to another trailer. All lights worked.", (from post #1), and all lights worked, you can almost assume the truck fuses are good.
Now chase the pigtail on the camper, back to the electrical junction box, open the cover, and inspect wiring there. The brown wire should be for the running lights. Remove the wire nut, and check for voltage, with the camper plugged in to the truck, and running lights on. Don't let the bare wire touch anything. If you have voltage there, report back, and we'll list some more checks.
2012 Ford F250 ext. Cab 4x4
2002 Jeep Wrangler Sahara
2008 Yamaha V-Star 650 Classic
2008 Work and Play 18LT