Was bored and had thoughts about LD

[TouchandFeel]

The lowest impact "solution" is to just simply remove the "you die" part and keep everything else the same.
It would then basically be just like Holmgang with a longer recast, an up to 10s buffer at the beginning, but with the caveat that if you receive front-loaded burst healing that equals 100% of your HP pool you could cut the duration short by dispelling Walking Dead.
Give a little wiggle room to the activation period while taking some from the deactivation period.

Boring but at least it should be easy to implement and it gets rid of the biggest issue with LD.

While a "Convalescence" type effect being added to LD lessens the healing strain, it still has two major drawbacks. First it doesn't really solve the "you die" situation, it makes it easier to avoid but that spectre of doom still hangs over your head. Second, the easing of healing then comes with the trade-off of making it easier to prematurely cancel the Walking Dead state.
So on one hand it helps, on the other it hinders. Whether the helping part outweighs the hindering part, well that is up for debate.

... That is what the issue with living dead boils down to, so the simplest fix would just be to make it work like holmgang ...

As I said above, all they really need to do to make it basically like Holmgang is to remove the death aspect and keep everything else the same. The other aspects like the 10s Living Dead before Walking Dead buffer plus the Walking Dead effect being removed if 100% healing is reached should be enough to differentiate LD and Holmgang.