I know, I know, I felt a bit odd even writing that I think that you’d be surprised at how much light even 2-3W of decent LED power can produce in a small space - for a trunk light it may even be worth using 2 or 3 lower power LEDs in series spaced around the trunk, so that when you have something bulky in there (gagged Mafia stooge for example) the light doesn’t get blocked. Even adding a light to the trunk lid to light up the area behind your car might be an option too, I know that I like that on mine.
here’s the build thread for my front dome light
If you want any pics of the rear one, just let me know.
Looking forward to seeing what you get up to and how you fix the timer issue