One way I thought to tune the balance of an asymmetrical mission I'm creating on Altis would be to add some scripting to prevent my conventional OPCOM from tasking any armour or air units that are initially placed under its command to certain objectives, depending on conditions. I don't really know where to begin with this, so any advice or guidance would be appreciated.

You have quiet a few options. One would be turning your conventional force to light infantry, then after a certain amount of time. You could spawn in profiled armor or air groups, which OPCOM will then take over after a certain time.

Thank you for the suggestion. Using only light infantry in the placement modules won't suit my goals since I still want a combined arms force to be profiled initially since players could reasonably travel to military objectives where the OPCOM should have those units garrisoned. In addition, ideally, the OPCOM would use those assets to protect or recapture certain objectives, but wouldn't use them outside of given TAORs under normal circumstances.