I forgot to add that I do not use pulleys in the corners I just feed the insulated wire through an egg insulator and allow it to slide, a bit of Teflon spray helps. Unfortunately with pulleys the wire can slip off the roller and get jammed up, it needs to be able to move a little in high winds or it may break.
I have had this loop up for 20+ years and apart from wire breaks and minor repairs it has worked well.