If I may throw in my 2 cents; I'm also pretty passionate about DRK and as a job, far from content with the current iteration.
With Living Dead, a lot could go wrong with that cooldown as from the time it's pressed to its resolution is out of your control which I think is counterintuitive for it to be your own personal cooldown that serves as the obligatory level 50 "last stand" ability. From the onset, I'd reduce the "Living Dead" status to 6 seconds and have a sort of anti-healing from any actions outside of your own. I think the anti-healing status would serve to ensure you die to proc Walking Dead and is a throwback to the anti-refresh status Darkside had. An in the situation it gets accidentally pressed, narrowing it to 6 seconds is a lot less punishing as it'll fall off faster.
For the Walking Dead status of Living Dead, it would also have this anti-healing debuff on it, but DRKs would have to only heal up to around 15-18% of their max HP to dispel the debuff or they'll still die once Walking Dead expires. I'd like if Living Dead wasn't tied to dying, but I get why Yoshi P doesn't want to take off the death penalty with how ingrained it is to this game's lore of the job. I know a lot players don't care about that either. I'm fine with both. But ultimately what I want is for Living Dead to be fair to DRK as their cooldown. Putting the burden off on the healers is extremely unsatisfying for both parties involved. Isn't even balanced to the other 3 tanks who're capable of essentially paying for their own tank invuln with reliable self healing or just the simple fact they don't auto-die once it's expired. I want DRK to be a little more self sufficient to do the same by reworking it to have an extended duration (approx. 15 seconds) and better self healing or "life steal" with it's toolkit. "Muh stronk TBN" is fine, but in situations where you would need to use Living Dead instead, TBN is then useless. DRK needs real sustain or there's nothing that separates it from being just an edgier, less damaging, bulky DPS job in those situations. I know DRK is gonna always have an edgy spin on some of its abilities, which is why I'm fine if a DRK still dies should Walking Dead expire, as long as they have the tools to avoid it themselves.
I think that DRK is currently resolves around The Blackest Night a little too much tat the est of its kit is very off balanced offensively, defensively and in its endurance. I think each of its level cap abilities need to be fine-tuned and strong overall for its kit, not just TBN.