There is one feature missing in 'Notifications Services' to make that possible with the SJA alone. And that is the option to to execute SQL from an external file. We plan to add this feature but not with high priority. It is not scheduled as neither 1st nor 2nd priority.
The workaround: Schedule a batch file calling
1) a SJA Backup Job
2) a script/program executing the restore to 2nd machine
3) a Notifications Service job executing 'TRUNCATE table …..'