I specifically called out "outside business hours"... there should be no overlap. I also don't tend to work on anything
near what I work on at my day job. Same for side work to main job.
Again, it depends on the work environment. I haven't had trouble getting permission when I've wanted/needed it. It's generally if your job performance is suffering, or if you are working in an adjacent or competing market.
You've specifically mentioned two things I believe I excluded in my statement.