PeopleTools Upgrade on DB versions not directly supported

I am working with a customer who is about to perform PeopleTools upgrade from 8.52 to 8.55.

They are currently on Oracle database 11g (11.2.0.3) want to move to Oracle 12c (12.1.0.2.0) as part of this upgrade.

I checked the DB versions supported for source and target PT version and it is as bellows.

PT 8.52 - Supported Oracle DB versions - 12.1.0.1.0, 11.2.0.4.0, 11.2.0.3.0, 11.2.0.2.0, 11.1.0.7.0, 10.2.0.5.0

PT 8.55 - Supported Oracle DB versions - 12.1.0.2.0, 11.2.0.4.0

Oracle database version common for PT 8.52 and PT 8.55 is 11.2.0.4.0, since this is neither their source or target version, customer is inclined to perform the upgrade on a DB version not directly certified for PT. E.g. 12.1.0.2.0 (which is supported for 8.55 but not for 8.52)