I agree with you that you want to be able to attach it on at the tree. I have been looking high and low for something that you hook on to the rope and not have to thread, but no luck yet. I think that is what @drew13 was trying to accomplish with the cranford step in another thread. I suppose you could cut a slot into an ameristep but it would probably weaken it too much.?
How did you get those Ameristeps on the WE ropes?
Here's a wrap around the tree.