The way I see it is, the planner and leader has it all worked out; how it's all going to go down, where and/or how they are going to dispose of a body, hide the truck, dispose of evidence and whatnot because they are the person with the means to do so. DM had everything needed for the job.
Just an example, say someone wants to host a dinner party in their house for friends but they don't have food, china, stove, table and chairs nor the space so they go ahead and host it at their friend's house without their friend's consent. That friend comes home to find everyone in their house, eating their food and using their furniture and fine china. No, logically things don't happen that way in the real world. If you're going to host a dinner party, one makes sure they can accommodate. DM was accommodating IMO. He made sure he planned it out and made "accommodations" everything from how they were going to get to TB's house (in his Yukon), to who was going to drive TB's truck and who would follow in the Yukon, who was going to murder TB and how, where and how to disposed of TB, hide and dispose of evidence. In his head he had it planned with MS but forgot to tell MS TB was going to be murdered. IMO if anyone thinks DM was a weakling in that sort of way, to be taken advantage of by MS, they may want to reconsider. IMO DM was arrogant (showing up without a disguise at TB's), figured he would never get caught, thinking his description was too average, whereas MS was a chicken sh@t and acted suspicious/nervous/scared (wearing his hood up).
IF TB's truck was the motive and MS was the one who wanted TB's truck (which I don't believe), why would he hide the truck inside a trailer belonging to DM, in MB's driveway, trusting DM would let him have it after the fact? And where in order for him to get access to it, he took the chance DM may not have given him the keys to the trailer, or MB may not have allowed him to tow the trailer away not knowing something valuable was inside and knowing it was DM's belongings, without DM's consent. IF it was MS who wanted the truck, he would have made certain it was in a place which he had easy access to it, like in his mother's garage for example. Also, DM got the incinerator for a purpose and IMO it wasn't for incinerating animals or brush on his farmland property, where he likely rarely visited. There are more inexpensive and legal ways to dispose of or incinerating small animals and brush than an official animal incinerator.
It would not surprise me to find out DM considered using the incinerator to get rid of his father also, then claiming his father disappeared. But being the planner and intelligent guy that he is, I am sure he would have given it much thought, weighing everything out, and came to realize he would have blown the whistle on LB's disappearance. LE would have certainly put two and two together then and DM knew they would. DM had two people closely connected to him who just up and disappeared. I am most certain LE would not have brushed off WM's disappearance the way they did with LB. A man with great wealth just up and disappears? LE would not have let WM's case slip through their fingers, no way, no how.
ALL JMO.