• Head yourself on over to Nexus Mods and get the Rockstar Purger[www.nexusmods.com] posted by pogobucket.
  
  
• Do a Manual Download of 'the manual way' (3rd file).
  
  
• Head on into the file you just downloaded and into RDR2\x64\data and you'll see a startup.meta file. (They give you a version for GTA as well)
  
  
• Open up the startup.meta with your notepad program and scroll down to the bottom, and where it says "REPLACE ME", Change that to whatever you feel like.. If any of your friends follow the same process and put the same text in that spot, you can play together.
  
  It's extra neat that you're always automatically in the same session without needing to invite each other.
  
  
• Be sure to save your changes.
  
  
• Slap that startup.meta bad boy into your \Red Dead Redemption 2\x64\data file, likely located in
  C:\Program Files (x86)\Steam\steamapps\common\Red Dead Redemption 2\x64\data.
  
  
• Enjoy the online content without hackers and modders ruining your gameplay experience.

I am not responsible for Rockstar's incompetence if they decide to ban users for trying to avoid hackers.
Cooperative missions and free-roam events will not function unless you have others in your session to join with you.

I have about 55 hours of playtime online using this with some friends and nothing bad has come of it.