Swansea theres a council carpark always open at blackpill quiet at night and a large carpark in mumbles at verdis icecream ,cafe im there all night fishing sometimes turn in before the pier .drinking water tap there last time i looked.
Gower check out the heritage centre at parkmill water,toilets and may find a spot there if you look or ask, top entrance to bankfarm site at horton get water and go, grass verge parking for pavland cave on main road to rhossilli is good. theres a field carpark for whitford open all night put money in honesty box
Tenby loads of little laybys and good spots you see as you go and up the road to manobier to.