I finally decided to finish my previous take on toggleable stealth fields, after more than a year. Now it actually works as intended, with new features, optimized scripts, and a HUD Widget.

True Invisibility overhauls the Stealth Field mechanics from Fallout 4 with some inspirations from other games, like Deus Ex and Mass Effect. Now using a Stealth Boy makes you truly invisible, so you can sneak through a raider camp without worrying about getting seen. Also, you can switch off your stealth field anytime and on again afterwards, therefore not wasting a Stealth Boy for a quick leap. Refer to the videos (sry for the cancer quality) to see what the mod does.


Improved Stealth Field Bonus: Depending on the stealth device, you'll get different bonuses:

• Improved Stealth Field Bonus: Depending on the stealth device, you'll get different bonuses:
• Lightning no longer affects detection (since you're virtually transparent)
• Reduced movement impact on detection
• While sneaking, detection is much more difficult
• Reset combat for distant enemies (similar to Sneak Rank 5)
• [Configurable] Silent running (Power Armor excluded)
• [Configurable] True Invisibility, i.e. you're completely undetectable, while sneaking and not attacking (only for Stealth Boy variants and Chinese Stealth Armor)
  

Improved Stealth Field FX

• Better Sounds for toggling Stealth Fields
• [Configurable] Better transparency shader: The Pip-Boy is readable again, and while aiming, the shader (not the invisibility effect) is temporarily disabled. 
• [Configurable] Additional Animations for toggling Stealth Boys (can be turned off)
  

Toggle Stealth Fields (requires MCM's Hotkeys)

• As long your stealth boy isn't depleted yet OR if you're using the PA Stealth Boy, the Chameleon Legendary or a Chinese Stealth Suit, you will be able to switch the stealth field anytime
• [Configurable] Adds a duration penalty everytime you switch on the stealth field
  

Alternatively, you could bind the following command to a key with FO4Hotkey to achieve the same: cqf TI_ControllerQuest ToggleStealthField

Configurable Stealth Boy (for both Stealth Boy and Railroad variant) and Stealth Suit duration

• [Configurable] Automatically use another Stealth Boy when the remaining time is near zero
  

Different behaviors for different stealth devices

• [Configurable] Stealth Boy Duration doubled and benefits from Sneak Ranks
• [Configurable] Power Armor Stealth Boy drains Fusion Core
• [Configurable] Chameleon Legendary drains AP, depending on the number of worn pieces
• Far Harbor Cloaking Legendary now triggers on any hit event (instead only on melee hits) and gets the same bonuses as the Chameleon Legendary
  

Chinese Stealth Suit
While True Invisibility doesn't include a stealth suit itself, there are several patches for different mods that actually add a Stealth Suit item: 

• Creation Club Chinese Stealth Armor: The Stealth Unit is damaged when you stumble upon the suit, it requires repairing to regain some basic functionalities. It can be further upgraded to be more efficient and more self-sustaining.
• (the Repaired Stealth Unit functions just like the Chameleon Mod, the Military Grade Stealth Unit offers better cloaking capabilities, but relies solely on Stealth Boys to function and the Reverse-Engineered Chinese Stealth Unit adds recharging features on top).
• unoctium's Chinese Stealth Suit
• Armorsmith Extended's Therm Optics
• [Configurable] The unique Chinese Stealth Armor can replenish it's stealth field, but can also be recharged with Stealth Boys
  

• [Configurable] If you have Deacon's "Cloak and Dagger" Perk, the Stealth Field will sustain for a short time after attacking, before shutting down eventually
  

HUD Widget showing the remaining duration (for Stealth Boy variants and Chinese Stealth Armor), requires HUDFramework (obviously, but no hard requirement)

A handy MCM menu to tweak the stuff above

Support for Canary Save File Monitor and VIS-G (patches conflicting items)

...and everything else I've forgot to mention.

All files are esl-flagged plugins, bundled in a FOMOD installer.

Uninstall

Run the console command cqf TI_ControllerQuest Uninstall.

Known issues

• When using a Stealth Boy while still at the full stealth duration (or more), you won't get extra time, but also won't get back the consumed Stealth Boy (so it's literally wasted). This is because I forgot to add code for returning the item in the scripts. I'll fix this in the next upcoming version. In the meantime, just wait until the Stealth Boy nearly runs out and then use another one. 
• Issues with the invisibility shader disappearing, under different circumstances. I'm trying to find the source of this problem.
• Some users reported that a selected number of MCM settings aren't saved/resetting. 
• When using a stealth boy the first time with True Invisibility installed, the activation animation could play twice, disabling the stealth field again. It should work normally afterwards.
• FIXED IN THE NEW UPDATE!
• Transfer Settlements' Settlement Boy has been reported to activate True Invisibility (by making you using one). I haven't encountered the problem myself, but try to disable this option or use another preset ("Stable" or "Rapid") if this happens on your save.
  

Please report any bugs you find in the Bugs section.

Future Plans

Expanding support for other mod added stealth suits (leave a comment!) I'm open to suggestions, especially about balancing. Just leave a comment about what should be improved and I'll look into it :)

Credits

Big thanks to user @Sigma724 for extensive testing and bug reporting!