I have to say I've never seen a harness being used over..Our lean-to's tend to be 10' to 12' to the seat and usually have a shooting rail all around..

I can only think of hearing about one serious accident where a guy got pitched out of a double when his mate climbed out and the whole thing slipped..I am sure there must be more but they are not common. I guess climbing stands, and tree steps ect are just more dangerous..