I did my CPL part time and now doing the IR on the same basis. Its not a problem at all as long as you focus and get on with it. Some schools do sneer at the fact that some of us have to do it part time. But from my experience you get more done on a part time basis than most full timers do. They spend most of the time sitting around in the school getting bored. Whilst doing it part time, you tend to crack on and get what needs to be done, done!
Plus then you have the bonus of being able to earn too, not be in a financial stuper like a lot are.