Cluster-to-Cluster replication using polling

Hi

I have two DCs (A and P), each of them runs its own ES cluster in Active/Passive deployment,
I would like to mirror all data from A to P continuously with latency as low as possible (up to 60 sec).
I try to avoid using another DB (such as CouchBase) as a primary DB due to the additional computing resources and complexity involved.

I can go ahead using the snapshot and restore mechanism, but I fear that P will not get updated soon enough.
I thought of writing a custom poller for changes that polls A for changes (for example, based on last poll time-stamp) and apply them to P (as suggested by Shay, see reference below).

Is that a viable option? Any drawbacks? Can you suggest another strategy?

References: