'just tie the ladder to whatever is there' what a stupid statement.You dont need to tie to a rafter. You can't even do that as the felt is covering it.
You are not trying to prevent the ladder being ripped away by the arm of God. Tying to a batten is fine.
And you dont need to use the same rope as they use to dock the Queen Mary. A washing line will do
None of this is rocket science. Just tie to the ladder to what ever is there - move a tile, tie the thing.