heres a nice little thought for you that was touched on earlier.
For all those who played the Original Red Alert, remember the V2 Rocket Vehicle? It fired a single missile which was massively powerful, but with a reload time insanely long and the actual vehicle had basically no armour. this forced you to bring it up, fire, and pull it back. Similar principle for Hailfire? bring it forwards, unleash your payload on a target, and retreat?
obviously, a few tweaks to the principle are needed to make it suitable for EAW. Since in EAW the attacker has no safe haven to retreat to, it needs a way to discourage fast moving units to hunt it out and just gradually chip away at its health (EG speeder bike). Thats where the smaller Anti infantry gun comes in. Its enough to discourage such attacks, but not enough to make a difference vs any offensive targets.