Hi Jon,
Some great lines here (recognise that poetic bent of yours) and this has the potential to be a great song. I think you're right on a 3rd verse, and there are a number of roads you could go down. You could go down the descriptive road:
An old guitar, battered and worn
Bearing all the hallmarks of a life lived on the street
Playing the streets for nickels and dimes
Dirty denim trousers, and old trainers on his feet
But perhaps better, a verse reflecting that he's opening his heart, and sharing his experience of life to passers by, who simply walk on by, e.g. Bears his soul to strangers, who just look and walk on by, etc, etc. Or a mix of the two
Feel free to ignore.
Mike