You’re not going to get full on angle of the fireworks from Frontierland. The parade follows the path of the day time parade so along the side of pecos bill, country bears, liberty tree. The construction walls and trees might hinder your view of the fireworks. If you want to see both, I recommend staking out a spot on Main Street curb ideally next to a trash can. Then once the parade is over you can step out in the street for the HEA.