Great question! Personally I wore this thong bikini to the gorge for a full day festival in July. https://www.amazon.com/gp/product/B010PMS6V2/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

The only issue was adjusting a few times to make sure anything wasn't falling out but at the time I was pretty self conscious about that so it's what your comfortable with. The previous reply had a great suggestion, I think that wearing an athletic thong under the swimwear would help with this one drawback.

Most rave clothes are made from some kind of polyester blend and same with swimwear, in my mind they are one in the same. I do see some swimwear at shows but at this point the line is very blurred so the rave wear/swimwear looks very similar unless I'm paying close attention.

Hope this helps :)