Hi @bnerickson ,
The xcp-ng part to Exclude VDI from snapshot has been done on XAPI project and can be seen in github https://github.com/xapi-project/xen-api/issues/4551 , but will be only embedded in xcp-ng 8.3 planned around 6 month (+/- 3).
For the XO part, [Backup] Use ignore_vdis param when snapshotting, I will see with the XO Team and Olivier to synchronize the delivery