Most rigs its safe to walk on the roof provided you are not really heavy. Some of the heavier folks use cut plywood or plans about 4' long to walk on to spread out the weight. I weight 180 and have never encountered a problem.
Jake my sidekick (yellow Lab) 10/04 - 05/20
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho