TLDR:

• use 0x custom difficulty (100% verified)
  
• don't play solo
  
• use cursed items
  
• check game files for progression

I have decided to make a complete guide to the Lighthouse Keeper Badge, after completing it myself, comment if you wish to add anything.

You can use any difficulty you want, I have verified this with many people including me, for changes in future read patch notes[steamdb.info] after build 14936004 [steamdb.info]and/or check Phasmophobia Discord.

Anyhow, this is the best preset in my opinion:

• Starting sanity: 100 - so you can use cursed items
  
• Sanity Pill restoration: 100
  
• Sanity drain speed: 200
  after using cursed items, get your sanity to zero
  
• Sprinting: infinite
  
• Player speed: 150
  
• Roaming frequency: Low
  I think this will increase chance for DOTS state/UV ext.
  
• Changing favourite room: None
  
• Activity level: High
  
• Event frequency: Less
  less annoying ghost events+check for Thaye
  High may have its own benefits
  
• Friendly ghost: On
  
• Evidence given: 3
  
• Fingerprint change: 100
  
• Fingerprint duration: Infinite
  
• Weather: Clear
  on Clear: use freezing trick mentioned later
  on Show: you may get freezing earlier
  
• Doors starting open: None
  
• Monitors: On
  
• Fuse box: On*
  
• Cursed Possessions: All

I don't recommend running this challenge solo, you will spend loads of your time taking multiple trips to truck, cursed items and waiting around for dots, that means it will become boring very fast.

• Head Gear
  
• Ghost Writing Book - place it as soon as possible
  
• Video Camera
  
• D.O.T.S. Projector
  
• EMF Reader
  
• Spirit Box
  
• UV Light - UV on top is quite hard, bring tv remote and salt

second trip to truck is unusually unnecessary, but if you are lucky with the ghost room be sure to take:

• 2st Ghost Writing Book
  
• 2st D.O.T.S. Projector
  
• Salt
  
• Salt/Thermometer - Thermometer is not very useful, you will most likely leave before freezing temperature will appear
  default temperature is 20C so if you get cold breath very early, it could be freezing evidence
  you can experiment with cold weather+breaker off, it should show freezing much earlier
  
• Incense - smudge the ghost room of activity
  
• and pop Sanity Medication

• Haunted Mirror
  
• Ouija Board - ask "marko" till you have sanity to rule out EMF5
  
• Monkey Paw
  as soon as you place ghost writing use "I wish for activity" and "I wish to leave"
  "I wish for knowledge" may be useful at the end, use it close to the front door
  
• Tarot Cards - can increase activity a bit

Head Gear, Book, DOTS, camera -> mirror -> place Book, check ghost orbs, place DOTS -> use monkey paw -> use ouija board or wait for EMF5 -> Spirit Box/UV -> wait/get more stuff -> use monkey paw -> profit

• C Drive > Users > [account name] > AppData > LocalLow > Kinetic Games > Phasmophobia
  
• decrypt your save file here: https://es3.tusinean.ro
  
• look for "lighthouseKeeperProgression"

• Polter is polter, wish its in the wine room
  
• Banshee - dots events will be directed to target player (60% it will actually target someone)
  
• Shade - shouldn't do anything
  
• Yurei door abuse
  
• Oni - no airball
  
• Goryo - take one step outside of the room
  
• Twins - twinteraction(in person+screen)
  
• Obake fingís
  
• watchout for Mimic
  
• Thaye - very active + ouija board