Ha-ha, good question John!
I know it is a tricky and challenging
But I believe there are ways to combine both desk job and side-hustle staying sane at the same time.
Companies always want you to be fully committed to your desk job. But what if you try to negotiate a free workday to do your own project?
Developers at Unicorn Platform have a one “startup day” per week. It is a day when an employee can work on his own projects for all day. It is not only good for a coder, but for the project too: because he/she gets a new experience and skills which can be useful at the main work.
AFAIK, Valve and Basecamp allow to spend 20% of work time on personal projects too.
Tell these examples to your boss and try to convince them to give you a free day too!
Also, time-management can be the answer. There is a guy on this forum named @KostjaPalovic . He is a father of 2 and he works as a full-time programmer. Yet, Kostja still somehow finds time to build his own product (https://appliku.com/). He also helps others to master Django by writing excellent guides in his blog.