Man, those Solar Auxilia really make me want to do an Explorator based Necromunda/Gorka Morka type skirmish campaign.
They just scream 'civilian 40k' to me - less obviously military in uniform, especially if you paint them up in brighter colours. Those infantry, tearing up the board in these....
Could even include Orks and Eldar Exodites in the game too. Oh, such possibilities!