I think I might know the inspiration for Harrier Du Bois

[Drunkenstein]

There is a limited release spoof movie from Poland called "Bułgarski pościkk" meaning "The Bulgarian Pursuit" the main character "Leszlo" looks very similar to Harry.
The movie starts in a similar way where Leszlo wakes up in his room which is devastated. Leszlo does not have mental problems like Harry, but he does have constant digestion problems. Leszlo also while seemingly incompetent does get his job done.