As long as all the stoppers that currently terminate at Filton AW are reinstated to ParkwayIts a bit of a ballache TBH - remember the old 581 did it. To Filton is ok as you come along, left and up the road to the car park, round and back out. From Filton, you can’t turn right so you have to go down to the roundabout by Asda and then back up.
Besides, I'm not certain why you’d do it? It would be be better to improve links and facilities at Parkway.