EV/ES viable for Freezing Pulse witch?

I'm currently playing a level 45 freezing pulse/herald of ice witch in rampage, and am wondering what kind of defense to focus on. I don't want to go life/MoM/AA - it's too many points and I've done it before. Chaos Inoculation/pure ES seems to get worse every time I play it - constantly stunned or frozen, no dodge or armor for mitigation. There really just doesn't seem to be a good defensive scheme for witches that doesn't require taking up a bunch of slots with uniques to counteract downsides that evasion and armor/life don't have (dream fragment, eye of chayula or auxium, etc) and still leaves you less tanky than non-ES counterparts. Admittedly, low-life Shav's ES is godly, but that's not viable for me in a new league right now.

Therefore, is ES/EV a viable build path, getting hybrid nodes and maybe a few life/mana combination nodes as well? Is there anything that won't require me to get uniques just to counteract the downside of not having a gigantic life pool? I'd really appreciate some suggestions and feedback here. Otherwise I'm going to go right back to a life-based ranger or shadow to avoid the aggravation.

You are most likely better off finding a build that fits what you are asking, a life build that isn't AA MoM or CI. If you are going Freezing Pulse as life, you usually want to go EB to deal with mana issues or use a bloodmagic gem and scale through Iron Will. In the case of MoM + EB, Arctic Armour with a pyre ring would help reduce reflect or you can stack spellblock which is insanely easy as a Witch. Rathpith + Stone of Lazhwar with the 10% spellblock cluster gives up to 45% spellblock.

Find a build you like and adapt it to suit you. If you find you can't make the build work then show people what you have and improve upon it or reroll something else. You could always just link your build here and tell people what you are trying to accomplish and why, trying to answer whether something is viable is a pretty empty question since the answer is almost always yes, of course you can.

Then let me rephrase: Are any popular caster builds using EV/ES successfully at the very endgame, or even pure ES? I haven't seen any discussed lately.

Pure ES is of course viable in endgame. You'll have to pick the eye of chayula to counter stun though. It's a bit surprising you complain about that as it gives you immunity without the need to invest a single passive point.
Aside from that i recommend block. If you went the usual way to both the templar and shadow side you can pick Spiritual Guardian, Mind Barrier and Shield Block. With a rathpith and rainbow strides you get decent spell block too out of it (and a good ES boost from the shield).
Plus: skel-totem is always a good defense. With 6+ skels and a totem up you have a factual 85% evasion in most situations (try getting that with gear).