Thanks for all the responses. I'm only going 2-3" deep with plenty of slack in the wire (read that here). I am also going to try the electric edger first. I still have one from my suburbia days, it's a craftsmen and hasn't run in I'll say 8 years. It's in our attic above the garage, I seen it still sitting up there a month ago when I was getting the fishing boat stuff down. The area we are fencing will be about 3 acres, across the front, 30' in front of the house, up both side 10' inside the property lines, across the back 50' behind the barn, 280' wide by 430' deep. So I need to pickup or borrow another 100' extension cord so between the house and the barn I can used that electric edger on the whole project. I'll get the edger down tomorrow , make sure she still works, give it a once over, I also have a couple of extra blades for it.
Now if the edger no longer runs or can't do the job then I will go with the box blade for the 3" trench If the ground is firm enough to get the tractor out this weekend. we've had a lot of rain this past week, not as much as the east coast, but a good amount. It's suppose to start drying out by Thursday
I did look at a subsoiler at KK's website, the TSC by me has them in stock according to thier site , still will go get it if all else fails. I think that edger will work the best in this weekends damp ,soft sod. thanks again,