Why would it have been harder to chop that truck in the hanger than any of the other vehicles they are accused if chopping there? The risk is the same every time, really, AS or anyone could have showed up at any time all along, which would have made it a poor choice for a chop shop, in my opinion.
In my opinion, when you have a group of friends together, you already have each other for your alibi, you don't need neighbours to notice that. And again, why assume that he would be so careful in some respects, ie, making multiple alibis for moving the truck, and be so careless in other respects, ie, leaving an identifiable body on his own property when he had a means to fully obliterate it?
For that matter, why hide the truck at his mother's at all? Why not park it in one (or two) of the vacant parking spaces at his multiple unit dwelling, where each tenant would think it belongs to another tenant, and no neighbours would really take notice as things always come and go in rental buildings. I can hear people saying, 'well, he wouldn't hide it there because he felt like the police were onto him and he thought that they wouldn't connect him to his mother.' But if he thought police were going to possibly investigate him and look around his properties, why would he leave a body on another property? Why not leave it in MS's driveway and share the possible heat, it is not like his neighbours seemed to care as much what happened at that house. Also, it took the police about twice as long to find MS as it did to find DM, his house would have been a better choice, in my opinion, after all, if anyone can find your mother's house in a jiffy, even if she's changed her name, it would be the police, I reckon. But it took LE almost an extra week to track down his friend.