I used the CK to "fix" Hangman's Alley as I thought it would turn out without all the trash/ruins around it.

Changes:

• Flattened the ground, and the curvature edging the buildings 
• Fixed up missing bits and pieces of sidewalk/curbs/brick flooring
• Cleared the raider structures
• Removed irremovable light sources that wouldn't go away after removing the barrels/cooking pit 
• Cleared most if not all trash piles and decals
• Removed the yellow pickup outside that posed a hazard before and after raiding the settlement
• Removed a vent system, on a roof which is above the workshop, for easier access if you bother to go up there
• Added a armor and chemistry workbench
  

Changes v 1.5:

• Nav meshed the area behind the chained door above the brick pile
• Filled in very minor holes of un-nav meshed ground
• Put some raider structures in the settlement as scrap
• Fixed raider spawns 
  

With the exception of the missing nav mesh for the area behind the chained door/brick pile, most of the area is pretty well nav mesh'd.

-The issue with settlers standing around and not going where requested must be because of their faulty AI. Seeing it for myself the nav meshing isn't as bad as i thought. Hopefully the nav meshing I did for the brickpile/chained door helps settlers move to the settlement through that path.

-The issue with settlers taking the long way to the settlement: prefered nav meshing. Most actors use prefered nav meshing which consists of roads and paths which is why they take the long way and not a trip through the forest where dangerous creatures lie. This is not an issue so I won't change anything.
I've put the loot chest near where it was supposed to have been.

If you find any bugs or something I missed out on, or have a suggestion, let me know in the comments/bug section