BIG-IP configuration sync between datacenters with a different network topology

This is a little unorthodox as you want to sync devices that are two distinct HA pairs. You would need to configure them as a single device group and configure HA groups to ensure the right DC is active in the event of a device failure - essentially creating a four device cluster.

K16947: Best practices for the HA group feature

The problems you may have is when a device group fails over, say your floating IP on the inside interface. Assuming that the second DC would not be able to reach these devices, the pool would be marked down and in turn, so would your VIP.

You could get round this by having both DC servers in the same pool, DC A marks DC2 servers down, DC2 marks DC1 down.

Essentially, it's possible without using extra kit, you just need to think carefully about your failover scenarios.