Ignoring all other modules, lets look at what can be (barely) fit on an Iteron IV. It is possible to put 3x Medium Shield Extender II on the ship along with a Medium Shield Booster II. With good skills, this uses 87.40 of 87.50 of the power grid (no tractor beam).

The passive tank for this would be around 18 hp/s and the active tank would be 30 hp/s (that would last 45 seconds). That isn't much at all - a poorly fit frig can break that tank. The biggest thing is the ~3400 hp shield buffer, but that is just a matter of time. The active tank should be ignored and instead go with more resists which would increase the effective hitpoints of the buffer tank.

For wspace operations, it really doesn't matter what you will have. You will lose the ship if someone decides you might have something of value.

---

Edit 6/7

To escape as a Iteron IV in wormhole space, you will need to first make sure you can escape. You will need to reconsider the 'all lows be cargo' and change that to having one or two warp core stabilizers. Even a wormhole scout will have some tackle ability. You may also want to consider an inertial stabilizer. The additional sig size for for an industrial won't make it much faster to lock on to, but being able to accelerate a bit faster can be important. You may furthermore want to reconsider the rigs for improved acceleration over cargo. Adding a Damage Control Unit II will also significantly improve survivability.

Next, ignore an active tank. Fit the mids with shield extenders and an invulnerability II to improve the resists.

If this is going to be a long term thing for you (hauling in wormholes), look into T2 transports at some point in the not distant future.

For moving around hisec, I usually fit the largest shield buffer that grid allows and then if I want additional hardening I fit a damage control and fill the lows with reinforced bulkheads (a situation where hull tanking is viable).

I find the shield/hull combo to be optimal for the following reasons:

• You maximize the ship's fitting potential (slots, grid and the abundant CPU).
• Allows the maximum buffer (shield and armor are mutually exclusive as both are grid heavy and armor and hull both use lows)
• 60% resists on hull from DC II makes hull tank effective.
• Since armor is not hardened, fitting cargo rigs does not dramatically reduce ehp.

With modest skills, I can get 12,000 ehp out of a mammoth and still have over 10,000 m3 cargo (which, if you are actually worried about being ganked is likely plenty).

I think its a matter of strength in depth, and shield tank the way to go so you still have some cargo expanders.
Use a low for a warp stabilizer instead of cargo expander.
Consider using a rig to boost em resistance.
As many shield extenders as you can fit.
If you have any grid/cpu left consider fitting an Omni ECM module if you do get locked up then you stand a chance of making them lose lock and making your escape.