3-database configuration

I have the following Data Guard configuration, on Windows 2008 + Oracle 11.2.0.4:

1 Primary database

2 Physical standby databases (one in the same data center, and another in a different data center).

We're trying to do the following while keeping the down time to a reasonable amount of time.

Move all 3 databases to new server (Windows 2012) and to Oracle 12.2.x.

My plan was to create the same 3 databases on the new servers as 11.2.0.4, apply logs as standby databases until it's time to change over to 12c, at which point I would make 1 of the 3 new databases into a primary, and the remaining 2 would become standby's. I would break-away the 3 new databases from the old primary seconds prior to the move, and shutdown the databases as a safety net (we could start them back up if the 12c upgrade fails). Once the new primary is set-up, I would do an out of place upgrade to