Foot Powered Edger

Well, I'm moving in less than a month! One of the things I have here is a underground fence for my dog. I love it, no unsightly fences, and she's good about staying in it. I dug the wire in by hand with a shovel 4 or 5 years ago. It took me way too long. So I was looking and the easy way is to get a lawn edger. So I've been looking at them, but I can't really justify buying a dedicated one just to bury my fence, so I was looking at weed whacker attachments, but people seem to have trouble using them normally (blown motors and broken shafts), so I doubt they would stand up to the abuse I intend to administer. I could probably rent a heavy duty one, and I will if it comes down to it. but I was looking and found this:
Amazon Link

People seem to like it except the blade bends easily if you hit a rock or large root with it. I think I can make a blade that will stand up to some serious abuse. Here's what I came up with:

I used some 3/16" x 3" stock I had lying around. I did 2x 3"x3" foot pads because I had 6" left over from the 12" blade. the pole is a 5' piece of 1/2" steel conduit. It seems to work pretty good in soft soil (yard), hard packed soil not so well (edge of driveway). It won't go through rocks, but I didn't expect it to. I doesn't bend. that's for sure. I don't know if it will work or not, if it does I think it will be quicker than the shovel, but harder and less fun than the edger. But that would cost a lot more than this. For a one time deal I think I'll manage.