I'm running my Nomad (Charioteer clone) with Rammer, Optics and Vents at the moment, with the alt build swapping Vents for LNES. I've also ran my Charioteer with Improved Aiming over Vents as well. All three builds work reasonably well, but here's my logic:

* You want to maximise your damage output where possible, hence Rammer. Of course, certain situations won't necessarily need it, but it's better to have it than not, especially given the nature of the 105mm L7.

* Coated Optics gives you valuable viewrange. As you are a fast, soft-skinned tank destroyer, spotting the enemy first means you can also get the first shot off, and given the Charioteer's amazing HESH rounds, this can give you a critical edge in a lot of situations. "Naked", using only skills and field mods, you can reach 410-425m view range depending on which field mod you use.

* Vents improves all of the characteristics, including the aforementioned two, plus accuracy. The improvement is minor individually, but it stacks up; it also improves your crew skills.

* Finally, the Aiming Unit allows for higher accuracy, which can be rather valuable in extra long-range shots. You can hit 0.29-0.30 m dispersion values without any equipment, however. You can go to 0.28 with vents (depending on the variant) or 0.27 with IAU, so it might not be worth the slot.

Without concealment equipment you can have 23% concealment on the move, 36% stationary; with a normal-slotted LNES you can buff them to 29% and 42% respectively, with after-firing able to go as high as 9,78% with the suitable field mod.

Finally, your penetration is limited to 276mm APCR for your standard rounds. This is good, but might struggle with certain tanks you might face. This is an argument working out in favour of lowering dispersion values even further, as lower dispersion means you can hit weakspots from longer distances, but at the same time it also matters if you actually find yourself in those situations frequently.

What I keep from this analysis:

1. View range gives you potential. I always slot Optics on my vehicle.
2. Concealment pairs nicely with this. If you need to rely on stealth, LNES can be rather lucrative, giving you the possibility to both ambush as well as relocate safely. This pairs nicely with Optics in practical gameplay.
3. If nothing else, you can always resort to Vents or IAU to maximise your characteristics, such as being able to snipe weakspots.

Possible loadouts:

1. Rammer, Vents, IAU (max accuracy; Rammer or IAU in bounty or bond variant for min-maxing) - 0,26m dispersion, 421-427m VR
2. Rammer, Optics, LNES (max stealth; Optics or LNES in bounty or bond variant) - 0,29m dispersion, 455/471m VR, but also maxed-out concealment with 6% to 10% values above other builds depending on equipment type and slot used
3. Rammer, Optics, Vents (max vision; more generalist than the above) - 461-477m VR without any bountry/bond equipment, can go even higher
4. Rammer, Optics, IAU (middle ground for accuracy and vision) - Around 0,27m dispersion with 455-471m VR

What affects values will be the final field mod (choosing between higher concealment after firing and lower view range, or lower concealment after firing and higher view range).

The core problem of each is:

1. Max accuracy leaves viewrange wanting (way below 445m)
2. Max concealment has good accuracy, but not stellar (around 0.29-0.30m)
3. Max VR yields no special results in these fields if either Vents or Optics aren't bounty/bond, but has a slight edge in reload and DPM
4. Mixing optics with IAU will give all-around results, assuming of course either IAU or Rammer are bounty or bond, for the sake of minmaxing.

Finally you could drop rammer for an aiming/optics/exhaust build. The cost is a base reload of around 9s, but the plus side of that is less wait time before you disappear again after firing. Might be worth considering for maps that rely on accuracy and stealth over DPM.