I just don't solo T6 w/ my JH WD. EHP too low. Dying even once sets you back too far on your runs. If you die 2-3 times your efficiency goes out the window. Until they fix skill bonus on SH bombs it probably isn't worth it to solo T6 with JH WD.
The only way to play it right now is to gear up to the point where you do 1/2 hp dmg to elites on T6 then from there transition to full CDR so you can do 2 SH as fast as possible.
Yeah, though your WD appears to be especially squishy, even with Uhkapian. I'm running around with ~10m toughness thanks to Horrifying Aspect, and with more paragon levels (for +Armor bonus) and some slightly better versions of equipment I already have I should be at just under 14m. I think that will help a lot with my survivability issues. Oh, and I'm using the Siphon rune on Soul Harvest which helps supplement my healing given my high HP and rather low life per second recovery.
And as far as CDR goes, I don't think it's necessary to stack all that much; Grave Injustice covers a lot of your cooldown needs. I mean, if you're one-on-one against a single elite or a rift guardian, yeah, more CDR is nice but generally speaking there are enough enemies and white mobs that lets you proc it. I can one-shot champions in the low-500 million range without Strongarm (and mid-600 with it), so if I've done things right and haunted and locusted the enemies nearby, killing them should be enough for me to get that second shot on the elite if it is necessary. Even if your CDR is in the 40s, you'll still have, what, 8 seconds left? 9 seconds? I don't know how it is calculated with Spirit Vessel; in any event you'll still be relying on Grave Injustice for the bulk of your cooldown reduction needs. And for my needs, Horrifying Aspect and Piranhado helps to cover any remaining downtime.
On the sort of rift I was on, I think it would just suck for any Jade Doctor between the layout (prison), the enemies (harpies, rockworms, dudes who fall on your head from the sky, meteors, insects), and density (low, except when rockworms showed up). I don't really think it would have helped me to have ~4X% CDR instead of ~33% CDR; the enemies still would have been nearly one-shotting me and I'd still be dealing with enemies standing too far apart (and don't mob you when you use locust swarm!) and I'd just be dealing with an extra second-ish less of cooldown.
*shrugs*
I could be wrong, of course, though I will say that I've seen more than a few Jade Doctors in videos and streams dealing with T6 solo... though none have had my special brand of luck with rifts. :x