I've been watching a number of pushing hands clip and am struck by how most of them involve transitioning backwards and forwards.
The problem with going straight back is that if the other person can follow you will find yourself trapped and the back foot and are sure to lose your balance.
If you sink first in your front foot hip without lurching forwards, you will then be able to make a hole and lead the incoming energy into your center so it can be returned.
You will also find yourself in closer proximity to the other person and be able to engage with them.
I'll try to film this at some point.