I have setup HA on one node so far, and so far so good. Although an HA cluster with one node is perhaps not that useful 
For the second node rather than build a new Freepbx system from scratch and do all the odd customise bits I’ve added to the first server eg configure up email, add UK voices and various other tweaks I’m wonder if it would be possible to clone the node I have (its a virtual machine). If I do that and change the IP, system name, change the Freepbx system ID and licence the modules we use etc, could I then add this node to the cluster as the slave server?
I guess I would need someway of telling this cloned not it is no longer the active/master server and them join it to the first node?
Any thoughts/suggestion would be gratefully received.