The usual pattern is work -> personal time -> sleep. Why not reverse personal time and sleep? So when you come home from work, you sleep (thus getting an 8-hour rest), wake up around 2am fully charged and then work on your bootstrapped business during your personal time. You'll get more than 2 hours. Finally, work time comes last.
This way, your business gets your best energy and effort for that day, you get more rest, and work won't notice the difference.