I never worried about the roof as I have seen several people on the roof at Nascar races and a couple on the roof at the factory. But that ladder held on with about 6-8 sheet metal screws into fiberglass always concerned me.
I have read many forum posts about this and have not seen anyone that knows for sure what the ladder rating is on the Berkshire. Some members have said there is a label on their RV ladder of 250 for some and 300 for others. Never read about one breaking, but then I have not seen anyone on those threads stating they weighed over about 250 lb.
I was hesitant at first but finally learned to trust the ladder. But after losing a few lbs I'm now much leaner than Phil.
My main problem now is not being as agile as I once was is transitioning from the ladder to the roof. Seems those top rails are narrower than most and closer to the side of the RV. Going up is not as bad as once at the top of the ladder I can crawl onto the top, but that first step coming down backwards scares the crap out of me. I once stayed up there about a half hour just figuring out how I was going to make that first step down. I guess I knew how, just getting up the courage to do it.