Personally, I think the burial site is mostly typical. It's a little close to the road and the dwellings, but it fits with Heinrich's character. His friend said he'd casually walk into a garage and rifle through the people's things. But, in a field at night while people are sleeping is pretty private. If there had been a dog creating a ruckus, he would have just gone to another field. He was a very bold guy.
To me, Heinrich mostly fits the disorganized/organized type personality. He had the trappings of the ultra organized offender with his military persona. Often, you'll see the sadists doing this, but Heinrich did not have the personal control or smooth command over others. He had to run out really fast and try and get somebody quick. He was impulsive. He took risks because of the urges of his specific paraphilia. It caused him to be less in control. He just got lucky most of the time. If DNA had been more advanced back then, they would have had him earlier.