I haven't put anything in the trunk, but that's not a bad idea. I have push button LED work lights that I use, and it would be easy to stick one in the trunk. I might have to look into that.
What I did do, was add some high powered LED light strips to work as back-up lights. I noticed that after I tinted my lights, my reverse lights were basically worthless (you can see them on in one of the pics), so I got a couple of 48" strips that we use inside toolboxes at work and put them under the rear bumper. I put them right where the diffuser and bumper come together, so they cannot be seen at all until they turn on. This means that I could only aim them firing straight down, but it still puts out more than enough light to let me see when backing up. I was meeting a freind a bar and he was pulling into the parking lot when I was backing into a parking spot. He came up to me and said "what the hell did you add to your car?" I asked him waht he meant and he said it looked like damn airplane lights. Success!!!!
I even put two strips on my trailer (under the extensions where the ramps hook on, so they can't be seen unless they are turned on), and also running the entire length of the fenders (up inside the fenders and firing down). When I throw that thing in reverse at night, it lights up behind me like you wouldn't believe and also completely lights up where my tires are so I can make sure not to run over anything. These LED strips are amazing!