My Dojo has classes 2 times a week, but Aikido is in my head all the time. I'm trying to learn to slow down and let my learning happen on the mat, but it's easier said than done.
That must be very frustrating. When I first started training in martial arts, I was lucky enough to be able to train seven days a week if I wanted to. It was very good to be able to just be a dojo rat and immerse myself in it.
I don't mean to say that your ideas are wrong, or that thinking about this stuff is wrong. I just don't think you have to do it. Is there a connection between maai and extension? Yes? No? Yes and no? Maybe? I don't know, but you don't have to figure it out in order to do it. And I think there is a danger in becoming too invested in a concept that seems internally consistent but whose anchoring in the real world is more tenuous. In one of my favorite books, the Supreme Being says, "They[humans] write books that contradict the rocks, then say that I wrote the books and the rocks are lies." The practice of aikido is the rocks; we can write our books about it, we just need to be careful that our books don't contradict the rocks.
About writing books (or anything): have you tried keeping a journal? I have a practice of writing down what we did in each class after class. I use a blogger client on my smartphone, but the tool isn't important -- the important part is to do it consistently and soon after training. I find that even if I start off thinking there's nothing to say, and I begin with a simple listing of the techniques we did, thoughts and reflections bubble up. Sometimes nothing much is produced, but sometimes I work through something that's been bothering me and make my peace with it, or think of something I need to ask Sensei next time I train...whatever. I recommend keeping a journal if you're not already doing so.