All the enhancements and fixes from 8.1.1 to 220.127.116.11 will be available with 18.104.22.168.
Installing the 22.214.171.124 patch and executing IRM (If you intend to use Open UI and new features included from the Siebel CRM version 126.96.36.199 innovation pack)
are sufficient to do successful upgrade.
Instead of cloning and connecting to the DB you could create a restore point and use it when needed. Always keep a level 0 cold backup before making any changes to the database
as part of pre-upgrade tasks.