Hello Nelis,
a simple (and unsupported...) but effective way to stop SWPM is to simply rename R3load.exe just before the import. The initial connection check to DB will fail and SWPM will stop with an error leaving the DB in a consistent state. You will have time to do you activities and retry the SWPM later on.
You must rename R3load.exe as soon as it is installed by SWPM, obviously this imply a rather quick action and at least a test run is required, but you should have enough time to do that.
Best regards,
Valerio