If you count Cub Scouts, which you may not be thinking of, women are very involved in the Boy Scouts. Did you ever hear of a Den Dad? On the other hand, when I attended Webelos Camp as an adult leader with my son, most of those there were men but there were a couple of women there who were running one of the activities. Later, or so I understand, there were a few women who were on hand as adult leaders because one was my sister-in-law.
We did have swimming at the camp, by the way, but it certainly wasn't nude. This was about 1990. When I was in scouts in the 1950s, we never went swimming anywhere, there being no suitable rivers or lakes, nor was there a YMCA in town.