I still don't see the family or anyone close to Haleigh disposing of her this way. When I say close, I mean someone who loved her. So could Misty do this? Yes, if she had the means to do it. Could someone she asked to get rid of a body, yes, as long as they were detached. I know I will get feedback on this, it is JMO.
One big reason I wouldn't think of the Croslins for this particular scenario is because they weren't originally from that part of the country and most likely wouldn't have thought to do that first. Weighting the body with bricks? Maybe. But stuffing it in a crab trap? Most likely not. That would probably be the idea of someone local to the area or someone who went crabbing a lot. I lived in south AL most of my life and went crabbing a lot and this still wouldn't enter my mind as a way to dispose of a body.
I'm with Dr Fessel on this one- I don't think they're looking for a body. Maybe some evidence tossed over the side.