Instead of trying to get rid of this time gap altogether which as far as I know, isn’t doable, we could attempt to reduce it as much as possible.
We could configure remove-system-map.service to execute our script every few minutes. This can be done by adding
Restart=always
RestartSec=5m
which would make it run every 5 minutes.
This would flood the systemd logs with “Starting remove-system-map.service” type messages though.
Alternatively, we could configure a cron job to execute our script every few minutes.