extension ladder to get to roof? How to protect roof edge?

im sorry about the dumb question as im new to this... I have a tall extension ladder... Im just wondering how I would use this to climb on the roof of my TT without cutting into the edge of the roof? I think even at the shortest section it will still extend past the roof...any hints or tips? I would like to get on roof to spray it off this spring... once again, im sure there is an easy dumb way to do this, but im all new to this..thanks again...