That's cool. I was thinking more in universe as aerospace can be used to counter artillery but they can also be used for fire support.
True, good point. However, their aerospace assets will be... busy elsewhere, either way. Clan Aerospace didn't turn out as effective as their Mechs and Battle Armor did, for some reason. Still, it's not like the defenders will know that. Oddly enough, and Orion (of all things) has the AA Quirk, too. It's just as surprising as the Hatchetman!
I thought about a Hunchback but range is important when facing the Clans.
Depends on the time point. In this case, the defenders won't know better until it happens.
With the players operating the Clans, you could replace the Locust and Stinger with the Griffin and Shadow Hawk. Then add a Goliath, Zeus, Striker, and or BattleMaster to the Warhammer and Thunderbolt for the battle lance.
That would be pretty solid, and might be in keeping with one of the one-planet polities which can employ a Regiment.
It's also something that would usually be see in an assault lance on the frontlines than behind the lines. I thought about a Stalker as it's pretty common but it would slow the unit down. Maybe a Striker? It was replaced on the frontlines by the Awesome but it still rugged and reliable. It's also fast enough to keep up with it's lance mates.
Funny thing about a Security Company, they expect people to come to them, so speed isn't that big a factor. Heck, I could even have a Lance of Urbanmechs be involved and it wouldn't be too far out of character. Still, as you say, Commanders like Assaults (and even Heavies) on the front-lines where possible. And since their job is to escort and cover an artillery park, speed isn't a prerequisite. Even Centurions and Enforcers could be considered for such work, provided they were available to be acquired.
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The Striker has the Easy to Maintain quirk so it'd be good for a support unit.
If I had one, it would probably work. Getting one isn't a priority, as I've never cared for how it looked, or really needed on before now.