Might I suggest to set up build lists for ground forces in skirmish/GC using existing units with placeholder names? for example
Federation.
Rebel troopers -Placeholder for- Goldshirts with First Contact Rifles
T-47 Speeders -placeholder for- Shuttlecraft (might as well just put the Shuttlecraft used in space there rather than make something entirely new, maybe with a higher res texture or something)
HTT-26 heavy troop transport -placeholder for- Hopper
T2b -Placeholder for- Skimmer
Halo Universe
Ewok with blaster -Placeholder for- Grunt
Wookiee -Placeholder for- Brute
Urai Fen -Placeholder for- Elite
Swamp Speeder -Placeholder for- Ghost
Swamp Speeder made a bit bigger placeholder for Revenant
Speeder Bike -Placeholder for- Chopper
TIE Crawler -Placeholder for- Prowler
T4b -Placeholder for- Wraith
AT-AA -Placeholder for- Anti-Air Wraith
AT-AT -Placeholder for- Scarab
AT-AA made a larger -Placeholder for - Locust
Grenadiers with blasters -Placeholder for- UNSC Marine
Mercinaries with blasters -Placeholder for- ODST
Defiler -Placeholder for- Spartan II