Okay...I just joined this conversation. Let me clear a few things up as I live about 1.5 miles from where this happened:
1. There is no real "ditch" on this road. There is a grassy shoulder and because these roads are basically one lane, people use the grassy shoulder to pass someone coming the other direction.
2. It is pitch black on that road at night. That said, there are gas burnoff flares and if he walked far enough back towards Luling, there are houses close the road that have lights.
3. Hard to imagine he was too impaired (prior to the accident) considering that he was able to get quite a ways down Salt Flat Road and navigated some very sharp curves on the way. Where he wrecked was more on a straight part of the road.
4. There are a ton of deer out here and especially in that area. If someone swerves to miss a deer, they could easily have the type of accident he had. Most people that have grown up in a city like Houston don't understand that if you can't stop to keep from hitting a deer, you shouldn't swerve to miss it...you just have to slam on the brakes and hope you don't hit it or damage your car too badly. Swerving to miss an animal can result in a spin-out of this nature.
5. There are roads that come off of Salt Flat Road near where to accident occurred, but many of them lead into oil fields with no residents. He may have taken one of those and gotten turned around way out in the middle of some pasture, but considering all the searching they did, I assume they would have found something.
6. The 2 abandoned houses closest to the accident site are falling apart and appear completely abandoned.
7. The backpack very well could have been in the "roadway" but off to the side of the gravel road and in the grass.
8. If he was walking back towards Luling and came to Pumper Road which is a right turn coming from the accident site, he may have stayed on what he thought was SFR, but ended up on Pumper Road, which would have taken him to a highway with a 65 mph speed limit...who knows what could have happened if that was the case.