Trying to set up multiple OS partitions, that both point to the same home partition, inside LUKS container

Encryptfs has been removed from 18.04, in favour of full disk encryption (LUKS). See here for confirmation. This means that my current set up of having an encrypted home directory on a different partition is harder to replicate.

Basically, I like to have two OS partitions (sdb5 and sdb6), that both have their encrypted /home directories on a different partition (sdb8), because it makes it easier to distro-hop.

How can I set this up, all within an encrypted LUKS container, when installing ubuntu from a livecd?

I want to replicate this set up within a LUKS container: