Hi Mike,
you may be aware that a lot of places are clamping down on overnight van camping, however I didn't see any restrictions along the (cul de sac) road that runs passed Penmaenmawr Sailing club when I was down there the other day, there are toilets too ( didn't check if open) it is just over the wall from the A55 though so there is a fair bit of traffic noise.
Also nearby is the car park of the Puffin Cafe ( cafe currently closed but lorries use the carpark, watch out for the potholes ) there is a foot bridge over the A55 to the beach.
Nice sandy lug holding beach along here!
There are a couple of apps worth looking at "park4night" and "searchforsites"
Happy van camping!
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we call it fishing not catching!