"He is almost eight and reads at a sixth grade level but really hates to write. I'm afraid that if I left writing up to him, he would never write."
We were just discussing this very subject at my local unschooling playgroup! One mother was talking about how her son is a voracious reader but finds it painful to write. She was worried about this until her husband (who is a writer) pointed out that he had been the same at that age, and that the problem was that he had nothing interesting to write about. So instead he spent all of his energy soaking up literature like a sponge, and learning about writing that way, and eventually he got the point where he had some of his own thoughts he wanted to record, and having that goal and desire made writing a compelling activity for him.
I'd never thought about it before, but it makes a lot of sense to me. I remember in school hating to write, and avoided it completely unless I was forced to do it, and even then did as little as possible, putting as little thought into it as possible. My total output was pretty measly. Now I write all the time (not by hand, though, I find it way too tedious.) What's the difference? Well, when I was in school I was being told to write so much on a certain subject (which would then be evaluated) or to keep a journal. Guess what, I still hate to write under those conditions. Every once in a while I am asked to do so (which isn't even as bad as being *made* to do so) and I find it to be difficult enough that I try to avoid getting myself into those situations. I have found, however, that I *love* to write when I am passionate about the thing I am writing about, and when *I* choose to do it.
At this point, though, you are probably worried more about the mechanics of writing? Well, when it becomes valuable or interesting to him he will want to learn how. Until then, the more he's forced to do it, the more he'll learn to hate it.
"However, his education is my responsibility and I don't want to do anything that would jeopardize his future."
But coercive instruction *will* jeopardize his future.
"I myself have been an unschooler for the past ten years and have learned so much, but my education IS unbalanced. I have specialties but still lack in certain areas. For example: I'm a great writer but my spelling is terrible. I sing well, but can not play an instument."
But how can you possibly know what will constitue a "balanced" education for him? No one can learn everything; we are all "unbalanced" in what we know, in that sense. So what anyone ends up considering a good balance is necessarily dependant on what is relevant to his/her life. What is a good balance of learning for one person (what is relevant to his/her life) may be a complete waste of time for me. That's why it's pointless to try to devise a curriculum for someone else -- the only way that any real balance will be achieved for them, is if they choose it themselves.