Hey Richard, glad to see you on here!
I think it's a great idea to compose a song with sections that leave the audience to imagine their own melodies. If you're hearing from your audience that they hear their own melodies and they like it then keep it up! I think the key is giving them a melody to start with, something they can build on. Some audiences may not respond as well so if you're in front of a new audience I would limit those songs and if there's a positive response then add more next time.
Thanks for sharing this idea, I hope to use it in the future.
wow . . . that is beautiful.
I have heard so much chunk a thunk guitar over the years (since the early sixties) that I have forgotten just how personal and lovely a guitar can be to a guy with talented fingers . . . very nice indeed.