Do you mind drilling/? You just simply need to bring the lower vertex to the edge and up, right? I think any extended mount would be (totally guessing from my desk here) at least 12" up?
Some more guesses, the wire elevates at let's say 40º, and let's also say (no idea on this) 15lbs of tension, which at the 12" extension would put a moment on the extension base at 12 lbs-ft. Doesn't sound like too much, but deflect that wire with a few limbs and you will see that moment increase maybe even by an order of magnitude. I think you may need to over-engineer that base to assume at least a 100 lbs-ft moment, a 1/2" diameter pipe puts lots of stress on said base and bar.
Correct my angle and tension assumptions if you like, but I think you may need to at least use a large diameter base for any vertical extension.
UZJ100 "Mama Kuiser" built to look cool for the soccer mom
FZJ80 über rare "Geen", cloth'd & locked