Roofs are a truss system. I don't know of a roof you can't walk on. Besides, in order to satisfy warranty, how else are you going to inspect, reseal etc the roof? We've walked on every one we've owned. Sure, they flex a little, but you're not going to fall through it. If you ever get to see any brand RV built, you won't hesitate walking on one. They may have 2-3 plus guys stomping around up there installing stuff.
John and Rebecca Dickson
Emma-8 / Little John-5 / Iva-1+
2013 Ford F-350 Lariat FX4, CC LB PSD, DRW
2015 Jayco Jay Flight 28BHBE (#8)