Glenn says:

The next question is what type of fitting should it be?

I've always liked the simplicity of a bolt through the end, on centre, with a
tang attached and free-rotating, long enough to attach a block to other end of
that will be above the pole when under tension (any ideas for improving the
grammar there gratefully received)
It all depends on the construction of the pole. Whatever, the end fitting must
be free to rotate so as not to induce torque into the tube. Simple is
better....

Steve