"Traveler" is just a tinkerer. Cf. Sandy Denny in "Listen Listen": "I am a traveler
By trade/I only have what I have made." Also cf. "The Old Changing Way": "We go where the work is me boys and we work where we can." So, as a starting point,
I have always believed the subject of the song was the itinerant life of a tinkerer.
"The winding road does call": the tinkerer must travel to conduct his trade. Never cracked the code of the third verse though.