Goebel Reeves recorded a different song called THE HOBO'S LAST LETTER in 1930. (Some records were issued under the name "The Texas Drifter" which was a pseudonym or sobriquet for Goebel Reeves.) I don't know who wrote it, but it's certainly not the same song that Bill Hicks wrote. This one is on a 4-CD collection called "Sounds like Jimmie Rodgers" (JSP, 2006). Here's what I heard in a sample from Allmusic.com:

...doctor just told me today
That in three months I'd prob'ly be heading
The trail to that land far away;
And so I am sending this letter
In hopes that at last you'll explain
Why one night in June you asked me
Not to come back to see [you again?]....