There is not a downgrade path. The proper way to upgrade is take backups of your code and database prior to every upgrade, then restore/revert your code and database at every upgrade point if need be.
For instance from 7.0.103 to 8.0, you'd take a backup of the 7.0.103 code and database and save it off somewhere. Then do the same for 8.0 after your successful upgrade. Same is true for a successful upgrade to 8.1 and 8.2 and finally 8.2.48.
When I do test upgrades, I create a backup of everything prior to starting my upgrade. Then after I get a failed or successful upgrade, I'll simply revert the code and database back to what I started with prior, works like a charm every time.