I often get the impression that the state troopers up here are just happy if you have working lights. In less populated areas its not unheard of to put lens repair tape over a flashlight and duct tape two of these to the back of a trailer as "tail lights."
For what its worth, the last few batches of tourist buses (MCIs) I've seen appear to have the top corner markers in back wired to light up with the brakes and turn signals too. I could imagine a cop arguing that a skoolie's 8-way lights are universally associated with a school bus as opposed to simple tail or marker lights. The obvious argument to that would be that your non-school-bus-yellow bus with lights behaving as tail and turn signals is obviously not a school bus. Again, to any sensible person with critical thinking skills, you're obviously not a school bus, but that doesn't seem to always apply to the police anymore..
Consider that, on a whole, the police today are far more impressed with themselves than they have any right to be. While you might not be violating any law, this might not stop them from ticketing you, arresting you, impounding your bus, etc. Being right does not make up for the time spent in jail waiting to prove it, nor the potential for damage from police-contracted (i.e., "don't have to care") towing companies.
That all said, I don't feel the need to worry about it here. In the lower-48 there's no way I'd have red and amber lenses on my 8-ways. Just isn't worth it to me to fight that battle, even though I know I'm right. Your mileage may vary..