I make my steps out of 2x6 between the runners under the door. I've got a couple I've installed the "porch" from southern outdoor technologies.Ours are just ladder for now. But one of our hunters can no longer climb ladders, so we're looking at making stairs, although they will be steep stairs. Someone posted a picture like that a while ago, but can't remember who.
We do have two "built" towers, with full stairs with typical runners, but those stairs and runners were astronomically expensive due to the long runners.