Data archiver: remove records older than x days

Hello,

We're trying to take advantage of the new data archiver to clean up the process list (pmse_inbox) of Sugar BPM. Our client would like to keep 6 months of process traces ("just in case"). 

None of the available filters can be used for that, and I don't want to log in their CRM every month to update the "before" field in the archiver rule. 

Any idea for a workaround? Can this list be extended like others? I'd like to avoid a custom daily job that does that. 

This project is on Ent Cloud, so it must be upgrade safe. 

Cheers,

Damien