Weed wacking sucks, there is no way around it. If you are going to do it right, I would suggest the best one you can afford, a straight shaft with with a harness to support it and allow to swing back and forth without holding the weight entirely with your arms. I bought a professional back pack leaf blower years ago and it is by far one of the best investments I've made. This would work:
FS 310 Bike Handle Trimmer - Professional Use Grass Trimmer | STIHL USA Mobile
Having been out to NorCal a few years ago, I was really disappointed in how lifeless everything did look in the summer coming from the lush green woodlands of PA. It looked like our winter here.