We have several HA pairs and wanted to do the config sync with CRON as well. I actually had time to discuss this with a case engineer about do this in a straight forward fashion without a lot of PERL script or other script.
There is a simple single command line option to do this within the BIGPIPE commands. The preference would be to do a PULL from the standby unit instead of a push to put the work on the standby unit with more free resources than from the active unit.
bigpipe fo | grep -q "FAILOVER standby" && nice b config sync pull