The Night Rippers is your baby, I'm just throwing in suggestions, hopefully in a helpful way. So you make the call. I can see where your coming from after you mentioned the five Assault and Beastman thing.
Yes, a BP of 20 does sound nice... ÂÂ

 ...Drop the pen and step away from the rule books. ÂÂ
Close Order Drill: At first I thought of the film Zulu. So I instantly thought of Volley Fire. However, the 40K rules talks about a line of steel and bayonets... (Despite it being an insanely outdated notion in a modern battle) So to stay true to the fluff we could use it as...
So long as each stand in the Mordian Platoon is touching one other stand the units in the platoon each gain a +1 Caf due to their training in close order drill. This will make them vulnerable to template weapons and area effects but could be pretty good in defensive positions.
If you would rather go with a more
The old IG Codex though talks about the Mordians putting out a prestigious amount of volley fire. So perhaps some sort of benefit to the to hit value is not to terrible an idea.
You might also want to consider some sort of Forming Up in the end phase too. In order to allow the stands to remain touching. It's getting messy though.
Die Hards: The ability to survive multiple gun battles in corporate buildings and airports?.. no, no, that's not it... ÂÂ
75% Break point is full of additional problems. Avoid!
+1 Caf AND morale when broken?
I like this one. (outnumbered in Close Combat would be hard to remember I think but so might this) A trade off in the cards will be needed to pay fo rthis somehow.
3+ Morale as the simple solution. It kind of clashes with the Cadian Iron Discipline though.
The Cadet Commissar special card sounds really good. Hard as nails. So long as it's a unique then I would be ok if faced with this.