What are some ways to balance work, hobby, and family?

I work in the Navy, which means I work longer hours than average. I also am making a comic book on the side, and it’s taking forever because my wife wants me to spend more time with her.
I love my wife more than my hobby, but at the same time, this is probably the first project I’ve worked on in years that I might actually finish. I’m afraid that if I don’t work too much on it, I’ll lose interest and it will die.
She suggests I make a schedule. However, since it’s not my job, and since I haven’t gotten a chance to bang out a single issue (let alone get a system down so I’m more efficient), I don’t even know how long I should spend on it. I’m really turned off to the idea, and I was wondering, does anybody else out there have a job, a home business, and a family that they juggle, and if so, how do they manage?
Is there something other than a strict schedule (which I’m afraid might make it feel more like work and less like a hobby) I could establish?