I agree that a good stand alone ladder is the way to go rather than using 5er mounted ladder. After inspection from ladder I have used a piece of plywood to help spread the load across a greater section of the roof. I perform what cleaning and sealing I need to do in expeditious fashion although our rig's roof is a walk on version according to manufacturer. Thankfully, most times I could do whatever touch up is needed to seal the roof seams from the ladder as I am not fond of heights and traipsing around on our rig's roof for any length of time.