In the garage next to the sliding glass door to the living space, there should be a bank of 3 switches. One for the ceiling lights, one for the 3 reading lights by the slider and the last one controls the light over the rear man door as well as the rear cargo lights. If the cargo lights don't come on with the flood light over the door, somebody forgot to hook the wiring up.
2011 Ford F-350 4X4 CC LB SRW 6.7
2013 Keystone Fuzion 315
B&W Companion Hitch
1 wife 2 kids and 1 dog