>>60035924How Shadows is my favorite release of his (it's really just one guy with a confusing project name), but it's really worth checking his other stuff to see how his formula gradually changes. As far as I remember, the first two albums are literally him playing guitar in his bedroom.
Pre-80s Leonard Cohen is obviously the paradigmatic sad and lonely folk guitarist, so I'm mentioning him since you didn't.
I would also recommend recent Matt Elliott's albums. The guy is as sad and lonely as humanely possible. He sometimes relies on more complex instrumentation, but at the core his songs are just guitar ballads and he often performs them solo.
There are also many artists closer to alternative country like Will Oldham (Bonnie 'Prince' Billy), Bill Callahan (Smog) and Vic Chesnutt, who all have large discographies and are pretty sad most of the time.
Then you can try some neofolk, perhaps starting with Death in June's "But, What Ends When the Symbols Shatter?". Not everyone's cup of tea, but the guitar and melancholy are there.
