We were there about a week ago and didn't have an issue (maybe 1 or 2) seen outside the trailer, but wasn't excessive.

Stayed the night of the 20th of April 2021. The flies were thick from 4 PM through dark when they subsided considerably. Very few around this morning.

Not that I recall. We have only been there fall and winter, not in the spring. This is a very dry area. Any water sources are fairly far off.

Never has been a problem when I was there, but I haven’t been there year-round.