I have some experience here. I have two large German Shepherds. My big boy likes the front seat and moves between the back and front all the time. He is also perimeter protective, so if he does not like you and you get too close to the car when parked, he would make any military trained dog proud. Hence a heavy use. I am on my second set of covers in about a year and half. The first ones were from Shear Comfort, a well rated and reviewed company. The covers recommended were the heavy canvas. Short of it, disappointed. These never fit well, and faded. Dirt got ground into them, as well as smells. I now have CalTrend
http://www.caltrend.com/ I got the pleather covers. Much better, better strapping and far better fit. The pleather looks great, and it really touch. I have had these 3 months and they still look new.
What is important is the material you choose. The Okeles do not seem tough enough to me. I think most of the commenters have light in and out, basic camping/overlanding use. That is a far cry from your needs or mine. CalTrend has a new material that is woven nylon, I think it is the Sport Tex, also look at the Tough Camo. Get smaples
. I have heard a lot of good things about the woven nylon. Call them and ask which is best for your need. I can tell you first hand the quality of material, craftsmanship is really good.