"The Reluctant Exhibitionist" is still my #1 favorite ENF story of all time. Thanks for mentioning the other two, as I hadn't heard of them before. "Natalie and the Sun Chair" was actually not at all difficult to find. Google knows All.
I'd also recommend McSkyy's "Mindy the Exhibitionist" series, anything by TorreTxt or Helmhood (both members here), Hooked6 (not sure if he's here or not), the "Jenny" stories if you want something light, Alec Leamus's age-regression tales if you're into that, "Park Ranger's Predicament", and I've written some of my own if it's okay to toot my own horn a little (and that's not a reference to the "Caught Masturbating" thread over in non-fiction
).