There's plenty of room for parking at the start, it's well tucked away, only local walkers seem to use it, or, certainly that was the case a 3/4 years ago when I did a section of the walk with my son.
I believe Glyntawe is the nearest camping SN842163.
Would you guys make a weekend of it? It takes me 1.5 hours to get to Pen Y Fan and about 2 hours to this walk so doing it in a day is straight forward. I may still do it tomorrow, however, this wouldn't stop me doing it as a meet.