Childcare is a necessary component of home schooling for me. I'm an introvert who needs time alone for my sanity, and if I don't get it, I'm a wreck. Once you decide to HS, but before you actually start, find at least one college student or HSing teen--and two or more are better to have available in case one has a difficult schedule one quarter or someone gets sick.
Also investigate childcare options at places like the YMCA. My YMCA offers 2 hours of free childcare every day, and while you have to stay in the building, you don't necessarily have to be exercising to use it. (Though they do usually offer water aerobics classes, if those work for your condition.) Bring your bills and pay them while he's at the Y. I also like it because there are other kids around then, so it's social time for them while I get some time alone. That helps a lot!
I'm assuming your son is GT right? If not, what I say next may not apply in your situation. But if so...As for the butting heads, often when a child isn't bored all day in a classroom, behavior improves. So if the difficulties arose since your DS6 started school, HSing could solve those problems.
However, if the two of you have always had trouble getting along, HSing might be a challenge for you. To be honest, I worry a bit about HSing my second child (who is 3.5yo) because he's not as logical and easygoing as my first child, whose personality is very similar to mine. DS6 is easy for me to communicate with, while DS3 is not so easy. I, too, worry that my teaching DS3 would not be easy on either of us. For now he's in preschool, and he will be next year, too. The following year I'll probably send him to a half-day, nonacademic K class, barring changes to the plan. But what we do for 1st grade is anyone's guess. We're going to take things as they come.
Oh, and be prepared right now for the house to be less clean than you're used to. You can make cleaning up part of your homeschooling day--schools do, so we do, too! But there's just always a lot of stuff that's out and a lot less time to do housework. If you're really not okay with that, then HSing will be a problem for you, I think. Some people just need a spotless house, and HSing is not conducive to a spotless house.
Fortunately or not, I'm not one of those people for whom spotlessness is required...You can tell by looking at my not-spotless house!
