Rambling response.....

I feel like I have a "reasonable level of fitness" (your term). I don't feel like I have a super high level of fitness; I am just super determined. I am also just lucky to have a good biking body - for some reason biking suits me and I am much better at it than running, swimming or ball sports or whatever. I could never do a marathon under 5 hours, but I can do a century in very close to 5 hours. Ball sports make me cry. So maybe I have a "reasonable level of fitness" overall and an exceptional level of cycling fitness?

Are women better at endurance sports? I have to say yes, as long as they're mentally tough enough. If you read the ultrarunning stats, women start to close the gap to men's times in the 50k range. Ann Trason holds ultra running records that men cannot match. I think women's bodies are built for long burn efforts (we have more fat stores and if we can use them we can theoretically go longer.) Unfortunately, I don't think a lot of women are tough enough for some of the truly ugly long distance stuff. You have to have a stubborn to the point of stupid mind set at times.

For a 200k, pacing and comfort on the bike are key. Cycling longer distances is as much about being able to be on the bike that long as about fitness/endurance. I guess it all goes together. But when you get to longer distances, you need to experiment with pacing and food/hydration to see what works for you. As you get more comfortable with longer distances, then you can further experiment.