No ! never walk on roof panel , you will make seams leak eventually
Side ladders catch & really damage body sides , rear ladders are better & to make things more secure think about having it hook onto roofrack & store away in side van .
saw one with a folded ladder stored on inside of one rear door , it hooked onto rack & rested on rear step . Very smart thinking !
I built a temporary bolted cantilevered platform using the stake pockets of my pickup. Parked alongside the Sprinter. Was able to remove my old solar panel by myself. Needed wife to steady new larger panel when I climbed up to the top level when I installed the new larger panel. Unbolted the parts and stored them for my next high roof install.