It is eminently doable to carry a single WH geared healer/dps through Asation HM. Just be clear that you are being carried.
Provided you have a good partner and are a good healer (as you say you are), Dread Guard is not a challenge to heal. One of the healers being undergeared is not a big issue, provided you both heal both tanks and don't try to divide the duties. Dread Guard only becomes a challenge when one of the healers is actually a terrible healer
Operator IX has very low healing requirements for almost all of the fight, so that should be simple as well once you get the mechanics down.
Kephess and Terror will be more interesting. Kephess throws out a lot of damage, and it's easy for a little bit of carelessness to cause a lot of raid damage. On the first phase of Terror, you will be solely responsible for keeping up your side for parts of the first phase. You'll probably be relying on your tank at that point to make up the gear difference when you're too far away for crosshealing. Second phase will be quite hard (lots of damage) but you can make it through with a good partner.