Roller Top Case Holder Self-building allowed? With photo

Good day, As the title already says, I wanted to know if this holder would be allowed in road traffic. The scooter is a 25 and the tail light which hangs down, is fastened to the very rear of the frame, at the trailer coupling. The holder is 55cm long and stands 35 cm behind the original tail light. Would this be legal or should it not rise above the case?