Hey quick question for ya PS guys

I'm a CFI currently and have a pretty sweet gig instructing (they pay quite well and it's very part time, only maybe 15 hours a month). I also am soon to start ground school.

I noticed that they say you need approval to have another job, and was wondering if any of the planesense pilots did this? Like is it near unheard of to fly on the side a little bit or is that common? I figure even though I'll be pretty dead after 8 days on, it would still be nice to get a little side cash with my 6 days off. I also have a student I'd like to take to checkride in the next few months but will understand if any side flying is a no-go.