I am glad that you have such sensitivity to ethics with regard to your writing plans. That tells me that God is working in your heart already. It is through his work, already progressing, that we are able to begin to see the darkness within us. Only by the reference point of light does darkness discover itself. As that beam creeps deeper into our hearts, and we try to correct our errors, we find that we are only able to mend the easy stuff. We come to a point where we can go no farther on our own power. We can try as we might, but we fall on our faces, painfully and repeatedly. It is good that we try. We should always try to be obedient to God. That is the frontier of our relationship with him, through Jesus. And this is how we become finally, thoroughly convinced that we are bankrupt in our virtue account. We cannot become worthy of a relationship with God by meeting his standard of perfection, or by fulfilling our side of an agreement. When we come to this point, the enormous value of Christ's redemptive gift begins to dawn upon us. This is where we can really surrender, accept Gods grace, and step, in faith, onto a bridge we could never build. This is where obedience with a new motive begins. It is not obedience based on fear of being disconnected from God. He is always there. It is obedience based on reciprocal love: a desire to please God and light up this path for anyone who will walk it.
I have only taken a few short steps along this path (usually, three steps foreward, and two steps back), and I will not say that it is easy. But it is deeply fulfilling and we always have help. It is easier for those of us who follow because the path is fairly well defined. It was blazed by giants.
I know this is a very round-about way of responding to your question, but there was a soap box just lying there.
I agree with those who encourage you to write your book. Writing clarifies, organizes and developes my thoughts. I hear others claim the same benifits. God is clearly calling you. The path to him may be paved with letters.