Painting army Last Wall

So I'm painting models a few at a time and want to do a Last Wall Protocol kinda thing. I thought of instead of full units as the different IF successor chapters to keep them primarily BT and a single model as various chapters in applicable units. It would be a kind of an exchange program/mini Deathwatch where each of the chapters would be providing their combat expertise to my Crusade. What are y'all's thoughts on this?

Examples:

Unit of Sternguard Vets in BT colors with one of the models being a Crimson Fist
Unit of Assault Intercessors with one as a Subjugator
Unit of Heavy Intercessors with one as IF