This is an excellent and very long article which answers a lot of questions, debunks a few theories (including a couple of mine), and corrects some incorrect information.
A plaid jacket, pocketknife, cellphone charger and towel were found in the ditch; no mention of gloves or muck boots. The yellow truck IS new, or at least new to Dave. The video from Marker 126 is clearly Dave and he appears to be alone in the truck. The friend feeds hogs and saw the truck both on the way and on the way back at 5:30am and 7:30am respectively; knew it was Dave's truck but assumed Dave was handling whatever the problem was.
I think potentially the most important part of the article could be this:
Sarah said her husband, who has high blood pressure, would often complain he was tired and remark, "I can't take this." But when she would respond, "Maybe you need to find another job," he would dismiss her suggestion.
That sounds a bit ominous to me.