I understand perfectly. I'm not sure what I can suggest that you haven't thought of already.
You could try to schedule time with him. Will he go for 10 minutes of one-on-one time with you everyday, with no distractions such as TV or kids. H and I do this right now, and while he sometimes gets pissed that I might use this time to either initiate a relationship conversation or sex, he has been very good about it. Occassionally, he will come to bed with a pissy attitude and literally look at the clock, but I let that go.
In the beginning, you may have to direct the conversation into areas that he is not comfortable with, but maybe the scheduled approach is worth a try.
