Painting with light at twilight

I photographed this stand of trees in a Louisiana swamp at twilight during my last photo tour there. I used a small, powerful flashlight to selectively illuminate the center portion of the trees. The original twilight sky was not bad, but I wanted a little color so I added a new background using the Sky Replacement feature in Photoshop. My settings were 20 seconds, f/11, and 640 ISO. I had to do 3 or 4 test shots before I arrived at the correct camera settings. I needed the long exposure to give me enough time to paint with light. There aren't a lot of vantage points from which to capture visually appealing stands of trees at night because foreground vegetation often blocks the view into the swamp. I find the best vantage points are often small docks that protrude out into the body of water.