I have a FT career in Product Marketing/Development for a major company, and do Sports and Event Photography in my spare time (Weekends and Evenings). I also have a family.
I personalty don't find it all that difficult to manage it. I was self employed as a consultant many years ago, and I am adept at running a business, so the overhead work in running my photography business is very low.
I make very good money at my day job, and supplement it with a part time Photography that is close to the average full-time Photographer salary. Probably could make a full time living at photography, but i would be foolish to give up a fully indexed defined benefits pension with only a few years left until an early retirement. When I retire I will do Photography fulltime
I am not really a vacation guy, so i use a good potion of my 5 weeks vacation for daytime photos shoots when needed.