Just for what it's worth, I do work full-time but have about a three-minute commute, no kids and zero other demands on my time. I live in a one-bedroom apartment, so no big house to clean or yardwork or anything.
The physical exercise, at 2 1/2 hours per week, is the biggest. Although I did specify reading and posting at SR daily (critical for me, I'd say), that might not amount to more than 15 minutes or so.
I really should have more than enough time to do what I've set out for myself, though I appreciate that some of you think it's ambitious!
Thank you everyone for the feedback and suggestions. I hope all of the discussion helps others put together a plan too.