With the dual tanks we had on our diesel pickup, the range was about the same as you're projecting - around 800 miles. Our break system was the two Jack Russells - They would mostly sleep whenever the wheels were turning unless (a.) someone (anyone) rustled a package that sounded even remotely like it had food in it or, (b.) we slowed down for traffic. As soon as we hit a traffic slowdown and passed an exit (with not another exit for miles), one or both Jacks would have to go. Always an interesting situation.