I never thought of Dennis' voice as patterned after Shel's, but now that you mention it, I think you're onto something.
RRHoF? Maybe, but Shel wrote many country hits. Why not the CMHoF?
Queen Of The Silver Dollar was first released by Doctor Hook on their second album Sloppy Seconds I believe, but you're right, Shel's songwriting art had country elements too. As had Doctor Hook. You will laugh about it, but in Germany Doctor Hook were referred to in the early 70ies as "country rock". That said, Shel has seen recognnition:
"Silverstein was posthumously inducted into the Nashville Songwriters Hall of Fame in 2002.[41] Silverstein was inducted into the Chicago Literary Hall of Fame in 2014."Queen Of The Silver Dollar is a great song, cinematic in its lyrical weight:
I don't believe that Dennis' and Ray's vocals were consciously patterned after Shel's demoed voice, but Dennis was only in his early 20ies when he met Shel almost 20 years his elder (even eye-patch-Ray was 12 years older than Dennis) and was according to his own words absolutely overawed by Shel's little everyday life stories and witty street humor. He felt honored to be allowed to sing those songs and probably just opted to sound as close as he could with his younger, more flexible voice.