A few points:
Right after DM was arrested, LE gave a very skimpy description of suspect #2, but they stopped talking about that pretty early on and didn't appeal to the public for help finding him, which I thought was odd. Seemed like he must have been cooperating with LE, in custody (which didn't seem to be the case), or deceased.
While it wasn't genius for DM to have TB's truck parked at his mother's house, you have to remember that he didn't think he was a suspect at the time, and a casual onlooker would probably not think the trailer held the stolen truck from this horrible crime, particularly since he was known to use that very trailer to haul vehicles for his recreational activities.
There is no way that incinerator was there for ordinary farming purposes. DM was not the hard working farming type- there's no way he had it for farm work purposes. He did not have livestock and he wasn't clearing brush. It also looks squeaky clean and brand spanking new.
When his lawyer announced that he was representing DM, I noticed his info said he specialized in murder cases and organized crime. TB hadn't been found yet, and DM brought in the big guns. I think an associate may have referred him? Not sure if I remember that right.
Regardless of the circumstances of his father's demise, traumatic though it may have been, it's doubtful that would turn a law abiding, morally upright person to crime- with all of his friends joining along. He may or may not be the ringleader, but I believe his bad behaviour has been escalating for some time. It looks like we're in for some surprises in this case.
DM would be doing so much better if he had spent the last 8-10 years of his life serving his community rather than indulging himself to the degree he did.