Then might I suggest you ask your local government to invest in better lighting at you local park so your kid can still play at it even when it stars getting dark. Or if natural lighting is a must, you can ask your school district to have shorter school hours during the 2 weeks around winter solstice. If that is impossible you can ask for more outdoors school activities during mid-winter.

But what I gathered is that what matters most for healthy sleep is not going to bed early, but rather to sleep longer in the morning and wake up with the sun. So if we move to permanent DST this behavior of staying up late might become more of a problem because of the early rising.