Stranded galvanized plastic-covered clothes line works very well for dog run cable.
A small galvanized pully with the same type of cable from it to a hook for the dog's collar can't be chewed in two either, and enough slack won't "hang" the dog. Small galvanized u-clamps hold it together. Just string it between two trees, buildings or posts. Loop it around a tree, or screw-in hammock lag bolts work well for end anchors.
Another alternative, albeit more expensive, is sectional "temporary" dog fencing for pens. It comes in very light weight aluminum chain link 5' and 10' long sections either 4' or 6' high (your choice, based on the size of the dog), and comes with gate sections. There is even a top frame for a plastic sun tarp cover over the pen.
One person can handle it and assemble it in any size and square or rectangular shape, or even diamond-shaped if you want.
The sections are simply clamped together top and bottom with special single-bolt double clamps that come with it and grip the pipe part of each section.
I just put a 20' X 20' one together by myself in short order (one side against my house on either side of an exterior door) for our 1.5-year-old German Shepherd that lives in the house. She's long ago housebroken, but still likes to take off unless she's on a leash. This "fenced pen" stopped that, and we don't have to take her out on a leash anymore. The three-sided pen cost less than $350 for six 6' X 10' long sections (two with gates). Got it at local farm supply place.