The sunrise/sunset line is the terminator. So, Sun-synchronous (i.e., passes every day at the same local solar time) LEO on the plane of the terminator.
Whatever it's called, it's a horrible idea. Want a ringed planet, you know where to find it. One of these days they will come up with a clever (?) plan to dismantle the Moon to give old Earth a ring too... until the rocks start colliding with each other and decaying into our atmosphere.