Summary: using resilience gear in the form of enchants and one or two pvp items will allow you to gain approximately 60 stamina at the cost of perhaps 1% avoidance and 200 armor and allow you to have more flexibility in other slots of gear.
Feral druids have some of the most aggravating itemization in the game. Almost all feral-specific gear has some randomly useless stat like intellect. The badge loot has haste, which is pointless for tanking.
But mostly, there is literally not a single piece of PvE epic leather gear with defense on it. Not one. There is one weapon that has it (Earthwarden, which remains the best itemized feral druid tanking item in the game), and then...nothing. Sure, the violet signet is good for druids especially. As are a few other rings and amulets. In general, a druid must get their 156 defense rating needed for uncrittability from the rings, trinkets, cloaks and amulets.
Which unbalances things in favor of the warrior, as they can throw in a couple stam trinkets, put in an expertise amulet (again with more stamina than a defense one) and some avoidance rings, and suddenly have a ton more stamina than a similarly geared druid. What to do?
The answer is resilience.
While you need 156 defense rating to reach uncrittable, you only need 103 resilience for the same mark. Resilience and defense cost the same in terms of itemization points, but the things with resilience seem to have more of them. For example, take the tanking glyph enchants. Glyph of the defender adds 16 defense rating; glyph of the gladiator adds 20 resilience. That one enchant is the difference in covering 1/5th of your uncrittability needs vs. covering 1/10th. Similarly for the chest defense enchant vs. the chest resilience enchant; both provide 15 value, but that resilience is 14% of your uncrittability, compared to 9.5% for defense.
What this means in general is that you'll have 53 points of ilvl to play with. What that could be, in general:
530 armor (before bear form)
106 attack power
53 expertise/hit rating
In practice this doesn't happen quite as much since you don't get to choose, but it gets close.
Now, what you lose with that 156 defense is avoidance. With 156 defense rating, you have 66 defense skill, which translates to 2.64% miss and 2.64% dodge. 5.2% avoidance is pretty substantial, and could not be gained back if the ilvl translation went entirely to agility or dodge rating. Unfortunately that's dealing with the notion that we'd have perfectly itemized gear, which isn't the case. What we have is compromise. And the best compromises are found in pvp gear.
An example: the best bracers for tanking druids are the Band of the Swift Paw, which with an enduring talasite provide 317 armor, 23 str, 22 agi, 37 stam, 10 int and 4 defense. Compare this to the vindicator dragonhide bracers with a shifting nightseye: 236 armor, 22 str, 22 agi, 35 stam, 19 resilience, 21 crit rating.
The big loss is the armor - you lose 81 armor. You also lose 10 int. But you trade 4 defense (2.56% of your uncrittability) for 19 resilience (18.4%)and 21 crit rating, which means that this item is 7 times better for reaching your uncrittability cap while adding more threat. The loss of armor does hurt, admittedly - but the uncrittability for this is huge, by comparison.
Comparing the other honor cost leather items is not as good. For the belt, we'll compare the Belt of Natural Power to the Vindicator's Dragonhide Belt, and the cost of that 26 resilience is 123 armor and 12 stamina (assuming shifting nightseyes for gems). That's a bit more expensive in terms of the resilience gained. For the boots, we'll compare the Footwraps of wild encroachment to Vindicator's Dragonhide boots. Here we get the same 26 resilience, but it costs us only 61 armor and 10 stamina. If you're wanting something different, you can also try the vindicator's leather boots, which makes the tradeoff 3 stam and 103 armor for 4 agility, 30 resilience, 19 crit and 40 attack power. That's a bit better in terms of what you're losing, though unlike the bracers and the belt, the boots do have potential upgrades.
If you go with the vindicator bracers and the glyph of the gladiator, you can take care of 37.9% of your total uncrittability requirement. This means you need a total of 95.3 defense rating - round up to 96 - to get uncrittable. If you enchant your chest, cloak and bracers with defense enchants, you get 39 more defense rating - leaving only 57 defense rating needed. The Violet Signet of the Great Protector is 19 defense. Slikk's Cloak of Placation is 16. The Greater Inscription is 10 defense if you're Aldor, 15 if you're scryer. At the very worst, this will give you 45 more defense, requiring only 12 more defense to reach uncrittable. This can be reached by a neck item or 3 enduring talasites, which isn't so hard. If you used the band of the swift paw instead, you'd have to get another 25 defense rating from somewhere. That's 6 more enduring talasites instead of 6 solid stars (a cost of 36 stamina), or not using the ring of the stalwart protector in favor of some other ring (for A'dal's signet of defense, that would be losing 30 armor and 12 stamina and about .5% avoidance). If you use the glyph of defense and the band of the swift paw, you'll end up needing another 40 defense somewhere (10 enduring talasites, or 60 stamina), will lose 18 stamina from the enchant, and will most likely be forced to use a neck and another ring or trinket slot on defense.
Is that worth it? For me, the answer was no. That one piece of resilience gear allows me to be able to swap out weapons without worrying, swap out necklaces for more threat or avoidance, swap out trinkets without worrying, use the two best rings in the game, use the best cloak in the game, and in general focus on gemming for stamina. I personally use the gilded thorium cloak instead of Slikk's, but I will likely upgrade in the future. Slikk's is a great example of the itemization that you can gain with; you lose 8 defense in exchange for 25 more dodge and 7 more stamina.
The big thing is that once you get this gear, you don't need to modify it all that much in the future. The bracers + the defense enchant can stay for the lifetime of TBC content. The cloak + defense enchant can also stay forever. The helm enchant is a glyph and can easily be replaced. The chestpiece won't be replaced often, but the enchant is easily redone. Enduring talasites are cheap and don't require a lot of changing anyway most of the time. And all your other gear doesn't have defense associated with it to begin with, so at best you may have to regem a bit here and there. This becomes especially true when you start gemming with epic gems; with epic gems every time you have to use an enduring gem you're sacrificing 8 stamina for 5 defense instead of 6 for 4. That's a worse ratio, so if you can avoid this you should do so.
Note that if you choose to use flasks of fortification all the time, you can gain another 10 defense rating. I don't like this; it means that I am crittable whenever I'm not flasking, which is quite often. But it's a personal choice.