The site just south of Paris is quite a good example to visit for the first time, providing your navigation skills are up to it. I have seen several single women there, of all ages, the average being perhaps 40+ to 80 years old. They have a large swimming pool (bit chilly for me unless its a hot day), sauna and turkish bath (steam room). There is a restaurant and space to walk and explore.
Nobody would blink an eye if you had clothes on or off.
The parking is on grass without markings but with electricity if you wish.
We tend to spend a night or two when travelling past the area, but you could easily spend longer and perhaps catch transport into Paris for a day out.
They also have tennis and I am sure other amenities. It is a fairly large site.
Take the plunge, people are the same with or without clothes... I just hate swimming with a costume on.