I don't understand why you think parking on the property and possibly contaminating the scene is preferable to staging in a safer area. They moved further into the park as not to interfere with people coming to enjoy the park and the Command vehicles being so close to the road were causing some traffic backups.
In other cases I've followed, if an acreage is being searched for bodies, the command center is set up on the acreage. I've never seen a command center set up 1.6 miles from a crime scene, and then moved farther away during the crime scene investigation.