Hi,
It is not possible combine all the three steps .
What is your DB size? If the DB size is more than 1 TB, then you have to do mulitple test migration to reduce the export and import time and then do the upgrade.
Try to do a test migration and upgrade and see how long the activities goes...See in what ways you can reduce the downtime....
You have to either upgrade and migrate or migrate and export... You can't do the three things in single ways.
Thanks and Regards,
Vimal