Could these actions not assist?
REARM
unitname action ["rearm",rearmvehiclename]
Unitname rearms at specified rearmvehiclename.
Rearmvehiclename can be anywhere on the map, ammo transfer is by magic.
Unitname does not reload weapon automatically if it had no ammo beforehand.
REFUEL
unitname action ["refuel",refuelvehiclename]
Unitname refuels at specified refuelvehiclename.
Refuelvehiclename can be anywhere on the map, fuel transfer is by magic.
REPAIR
unitname action ["repair",repairvehiclename]
Unitname repairs at specified repairvehiclename.
Repairvehiclename can be anywhere on the map, repair is by magic.
How about telling them to move to base?
What about disableAI "Target" ● (disable watching assigned target)?
Even if you disable the "MOVE" AI, the units will still move out to attack the enemy, unless you
disable the "TARGET" AI.
Or take their attention elsewhere?
unit(s) glanceAt position
unit(s) lookAt position