In two step STO Process, PGI issues stocks from Plant(A) to Stock-In-Transit of Plant (B). Since stock in transit already belongs to Plant (B), value is posted in the receiving plant during PGI. This is the reason why no accounting document is posted during Second step (GR) since stock (in-transit) is already part of receiving plant.
You cannot change this standard feature.
Stock in transit is virtual location and cannot be inventoried. Even if you show this inventory in suspense account how would you be able to prove that this inventory does exists without physical inventory. Wouldn't that be an audit issue?
Regards,
Niranjan