Hi Mickjen, Ever tried the nuddy beach at Morfa Dyffryn ? It's just north of Barmouth in Wales, fairly near Shell Island.
There are three camp sites very close to the naturist beach, One, Benar beach has a walled off naturist section, another (Davids field) allows naturists along the far edge so long as wind breaks are used. The other (Dyffryn seaside estate is more of a "Normal" family site.
All are within a short walk through the dunes to the official naturist beach, which is around 1km long and has lots of dunes.