so you're trying to die to friendly fire every fight? interesting mod idea!

LOL i also want this mod. but as @Tyr said you are gonna die to FF. Dont wanna spoiler events but plenty of em have Ally AI that spawns behind your other Allys or worse you. and than they will kill you and other allys before enemy.

My bet would be to look at the battle servitor talent you get from the forge world. While it does not work, its ability describes that it spawns a combat servitor when you spawn in a warp travel combat encounter. So taking that, you could copy the perk and change the spawn to guardsmen.

Though as said above, allies are notorious for friendly fire. So you'd need to find some way to remove FF or give yourself control over the spawned units.

As a fan of the table top, I am rather disappointed that this was just pathfinder 40k instead of like the actual table top.