My solution for this was switching careers. I found that anyone hiring engineers wanted someone doing 40 hours a week at least, which makes sense since you have to have such a large mental model to build a system. Content and copy writing on the other hand is much more flexible because the unit of work is so much smaller. Any content marketing manager would love a real engineer to write for their blog once a week and help sell their product. Then just stack up different clients until you reach whatever weekly load you are comfortable with.