Psalm puzzles

I aspire to writing good songs for all the psalms. In order to succeed, I am going to need to become a better musician than I am, on several levels.
1) I have generally been able to write word-for-word songs on the shorter psalms, and some of them are actually singable by a congregation, But what do I do with the longer ones? How do you write a song from a long psalm which a: avoids missing parts of the psalm, b: avoids twisting the psalm to fit one's rhyme scheme, c: avoids being tedious. I have been singing from metrical psalm books for some years now (The Psalter Hymnal, the Book Of Praise, the Book Of Psalms For Singing), and all of them fail on all three accounts listed above, more often than not.

2) I have a word-for-word (ESV) song written on the first 17 verses of Psalm 69, which seems to me to capture the sense and feel of the psalm. One day I hope to record it.

But it raises a question in my mind about the singing of psalms. Even though I feel I have musically captured the psalm fairly well, there is no congregation on earth that could sing it. How do you do angst and despair in congregational song without either obliterating the text on the one hand, or failing to match music to the words on the other? And how do you sing the whole psalm without it becoming tedious?

I believe the psalms need to be sung, with feeling, by the church. But I need to do a better job of figuring out how. I am not convinced that chanting is the final answer, though it may be part of it.