A lot of luck has gone into this case that it's moved along so fast. The fact that the forestry agent found the car so early in the case. The car was found before he was even known by law enforcement to be missing. I'm thinking because it's been so mild he was checking to make sure no one was up the forestry road. I don't know which one for sure but I have a guess. If it's the one I'm thinking, there is a small pond at the end and maybe he was making sure no one was back there fishing/picnicking...
There are hundreds of little Mark Twain natl forest only roads. These generally go to small natural lakes, fire towers, old logging roads...
The next bit of luck was that it was 70 degrees in mid Feb, sunny, no snow on the ground. This is not the norm for this part of the country. The family was going fishing because it was a beautiful day.
The roads in this area are narrow, almost no shoulder, ozark mountains with hairpin turns. If it had been a normal winter season no one would've been out. It's been a very mild winter.