I prefer San Felipe as well, not that I am fond of either. Rocky point is dusty and the parks there are pretty uninteresting. You might want to consider San Carlos (Totonaka RV), That is as far south as you can go without vehicle permits. All you need to do is get the 180 day visa. Get your Mexican insurance on line or at the border.
If it comes down to San Felipe or rocky point, pick San Felipe.
Single women, you should be just fine in any of those 3 locations, you may want to look at a caravan if you want to venture further down on your own later. I have seen single women traveling all over Mexico by themselves, but you have to have a different comfort level,