Don't worry, I got this.
Now, I finished some of the commander concept, It has the Kangaroo (I chose Churchill Kangaroo because I know relic doesn't want to spend manpower on making a Ram Tank Model.). an Upgrade to put a 2 in. Mortar on the UC, and possibly a 2 pounder UC unit or Anti-Garrison Infantry Sections (They have Satchels and Flamers, but can't build stuff unlike normal IS).
I don't know what to put for the last 2 ability slots. maybe Crew Repair and a generic off map Ability?
Churchill kangaroo was hardly used though