KA is an unknown quantity of this fight. We are sure the jutsu is not perfect, but we are not sure why. We do not know it's limitations or even how strong it is for that matter. We've only seen it used in action once and seen it used in a subtle fashion. The question then is whether it works as other genjutsus or if it operates like Izanami having special requirements to undo it. We just don't know it there are too many variables to really discuss this matter.
We also didn't get to see Hanzo at his strongest (which was a boneheaded move from Kishi) but his water jutsus were apparently legendary. And he could also strike fast enough to stop handseals as he once before beat Mifune. He was also able to fight with Chiyo on equal terms. His Summon would kill the Baku as the Baku inhales air his salamander exhales poison.
Considering then that both Hanzo and Mifune can strike fast enough to prevent handseals, and considering Baku is countered. I would say that Hanzo should be able to solo a KA less Danzo. Danzo also wears that cumbersome seal (though we don't really know why).
With KA it depends how it works.