I have been following a family of travellers in South Wales and know how difficult it is (Evans, Williams, Boswell and Lee) especialy as they married between families. When you talk about encampments, most gathered in places for a weekend or a week and then moved to the next. Those places are unlikely to be recorded. During the winter months, they tended to form larger gatherings, often close to industry where they worked; tin rolling mills or coal mining. I have pieced information together through newspapers, often court appearances for fighting or theft. But also to establish their ‘real’ name, as the name they were using was often not the one they were born with. Because of stigma, some adopted Welsh sounding surnames. Especially the Boswells!
Looking at the map offered, there is an area of land next to the school that could have acted as a temporary encampment. Were there links to the permanent fun fair? If so, they could be resident, possibly with large events during the year where many more would gather. There are older newspaper articles about gypsies in Rhyl. One of 1899 mentions, a Grand Complimentary Concert will be given on the above date by the Famous Rhyl Gypsies and Madame Marie Williamson. Another talks of Gypsies arriving from Epping Forest.