Need to upgrade my VE from version 10.2.4 to version 11.5.2.0

Your approach to the interfaces is fine and sensible.

I did fail to mention that encrypted passphrases used for off-box authentication will often not port. I usually remove items relating to LDAP, RADIUS or TACACS before deploying, and re-add them after the upgrade. I also failed to mention that HA changed considerably between 10.x and 11. That usually ports, but if not, I remove all HA config and rebuild it after a successful install.

I'm sorry to hear that you are experiencing so many challenges. For what it's worth, your approach seems quite sensible.