Great line of thought, here.
This photo shows the porch a little bit closer up.
About 4-5 tile rows down from the front wall and 5 tiles over, there might be some slight shoe prints, but it's hard (for me) to tell.
I'd expect there to be more smearing and footprints considering the amount of blood and the chaos of an abduction. If it was a straight march to a vehicle, I'd expect a more linear pattern. Was NG struck just outside the door, or was she delayed here for some reason before moving/being moved toward the road?
Carrying someone over your shoulder is really hard to do, though obviously not impossible. The masked man doesn't seem particularly big or strong, so I have my doubts he'd be able to do that. Now, with a partner - one holding the legs and the other the feet - it would seem more doable to me.