My female Golden lays like the last picture with the legs out behind her, but not all the time.
And Dugan, the Husky mix sleeps upside down on the couch, on the floor against a wall. I think there is a pic somewhere on this board of it. If I find it I will copy the link here.
I found the spot where the pic is.
http://www.quiltingboard.com/posts/list/4261.page
Kyia