"My kids team is doing 5400m of long race pace intervals (800, 1000, 1200s) five days before the state meet.
Can anyone top that stupid workout?"
Since you are well-versed on training methodology, and have vast experience that indicates that 5k of work for a high school cross country team five days before state is tooo much, you should probably apply for the coaching job yourself. Better yet, organize all the parents together, oust the current coach, and then you can coach as you see fit.
Or apply for a job at another school, take your child with you, and then you can coach your child to your heart's content. Either way, I don't care.
It's parents like you that make coaches who constantly sacrifice their time and energy, spend countless hours in professional development and coaching clinics, working as hard as possible to help your child reach their full potential, all while receiving minimal compensation (minus what we end up spending on the team out of our own pockets) all while teaching full-time as well, question why we do it. I've seen a number of potentially great athletes inhibited by their meddling parents, always questioning everything that is done. And in the end, you feel devastated as a coach when they underperform at big meets because their complaining parents have planted huge seeds of doubts in their mind. Meanwhile, athletes with supportive parents seem to excel while doing the same workouts/training.