I think the rehab property is a poor location for a search for a body. Let's assume something happened in the house (I don't assume that, but o.k.). Any parties' first thought would be get it out and away from the house.
Some have suggested the burn pit as a possible disposal option. Not likely, the fire pit does not look big enough to do the job. Sure a small pit like that used carefully over a long period of time, but we have to assume that time was of the essence.
There is a creek that runs along the back of the house, it crosses Miller Road then connects with Miller Lake at its North End. If there is any spot to search there ... and I am maintaining that there is not, look across the street about 50 yards in on the creek bed. Don't bother going all the way to the lake (the body would be too exposed there, and too heavy to get all the way down to the lake).
Other than that I don't think the outside of the rehab house would be too profitable.
Another key spot in Centralia would be along the tracks from the station to where the tracks cross a creek (concentrating on mostly the wooded areas). Other than that I believe if you search you keep on running into "could be anywhere."
I believe that in any case we are trying to find something hidden by someone with time contraints and who would believe that LE are coming any minute (which narrows the possibilities considerably).
I agree about the rehab house it would be foolish move to do anything there.
JAL have you been to the rehab house? Knowing about the creek I mean this is the first I have heard of a creek across the property. Or anything running to Miller Lake. Interesting thought, do you know how deep this creek is? This would be an easy way to move a body floating without being noticed. Just wondering if this runs across the Horse stables too.
I think the whole Centrailia story is dead end, too much proof Beth was still in Mt Vernon beyond that window of time. That is what someone called 'slide of hand' an old magicians trick when they want to make something disappear they draw your attention to the other hand, in the opposite direction while they make it go poof where you last saw it.
I do agree about your time contraints.