Wow, who said you were crazy for riding the Afan at night?!
Take a mobile with you, Y Wall is not technical at all. You’ve got a chance of knocking yourself out, but day or night you could do that.
I’ve ridden Afan routes in the night loads of times, I remember riding W2 at about 11pm, after having started riding at 9am at Nant Yr Arian the same day. Now, that was an adventure 🙂
There’s no big drops or jumps, so as long as you’re not riding balls out, out of your depth, then you’ll be fine. (lots of double entendres in there for you).
Take your lights, and a backup light, and a decent bag of kit and spares, and something to keep you warm in case you do end up with a series of punctures.