I am looking for a super-compact light to attach to the under-rail on my 4" XD. I haven't been able to find anything that doesn't extend at least a half inch longer than the barrel. I would love something that is either flush with the barrel length or even shorter. I don't need something really bright, or tactical grade, just something to have attached in case I need to pull it out of my bedside table one fateful night.. Any ideas?