Recommendations on replicating an RDS PostgreSQL instance?
I think that pglogical extension could be be used to solve your issue - in the future, when it is extended to allow a replication user. Currently it requires superuser privileges.


  pglogical is a logical replication system implemented entirely as a
  PostgreSQL extension. 


Also, from their documentation:


  Fully integrated, it requires no triggers or
  external programs. This alternative to physical replication is a
  highly efficient method of replicating data using a publish/subscribe
  model for selective replication.
  
  Use cases supported are:
  
  
  Upgrades between major versions (given the above restrictions)
  Full database replication
  Selective replication of sets of tables using replication sets
  Data gather/merge from multiple upstream servers