part-time jobs are definitely feasible, it's just a matter of that other job's flexibility in schedule. if you're going to commute, however, that makes it that much more difficult to find time for that second job, especially on reserve at the airline. xjet's policy is no flying jobs outside the airline, since any work-for-hire adds into your yearly/monthly limits, etc.
i know lots of guys, though, who work second jobs at pizza places, home depot, best buy, bars/restaurants and a myriad of other schedule-flexible type jobs. sad isn't it?