I do this. In all honesty, it is tough but not insane / impossible. I'm usually home @ 6:00 pm and with my daughter until she goes to bed at eight. I spend two hours with my wife until she goes to bed usually around 10. After that, rather than play video games, watch tv, etc, I work on a side business until one or two am in the morning.

I'm lucky in that my whole life I've been good with really only needing 5-6 hours of sleep a night so, when my daughter wakes up at 7:30 and I go get her out of the crib I'm usually good to go.

So, it's really a matter of prioritization. I play a video game once in a long while, read books slower than I used to, never really watch tv (but parenthood also removed that possibility) and I have the time.

Customers and customer support are where it gets tricky as you will be juggling two companies that operate 9-5. In that scenario I more often than not give up my lunch hour at job 1 to work on job 2.

Not saying it's perfect however, if you want it, it's there for the taking.