Once a Tanker is airborne and NOT part of a pre-established support sorte would it be a bad idea to ID this AC on the map in a different color than other planes if at all technically possible ?
When flying with offload fuel onboard this may assist airborne fighters wanting to remain aloft and are close enough to intercept and refuel (may use too much fuel to complete so distance dependant)
Once intercepted the contact and desire to fuel and acknowledgement may be made by cycling strobes on/off by both AC . If the tanker can’t comply no strobe on/off cycle.
KC-10 also carry cargo, personnel and medical support
as most of you know.
Flying as a random gas station is not a true to life mission profile but in IF …If you know where to find gas in the sky it may help.