Hi there
Firstly I am no expert at this but can tell you how I managed to get Harley to go down away from me.
I started by getting Harley in the down, on his lead by the side of me, and then progressed to dropping the lead and take small steps away from him, and returning and rewarding. Over time the distance between us grew, and then I would tell him down, and introduced a hand signal, I use my arm raised with flat palm facing the dog.
Now he will lay down away from me using just the hand signal, but on one occasion, the hand signal was brilliant, as through my local park, there is a concrete walk way, and on this particular day, a van was driving through the park, I was one side of the path and Harley the other.
I screamed, in shear panic at him down, and put my hand up, he laid down, and the van passed without incident.
Hopefully you can understand this.