Just throwing this out there but a friend of mine just bought a 2012 CC DMax LT a week ago for 42500. They said that they needed to move the trucks and knocked 8K off the price! I've been looking for used LMM LTZs and am having a hard time finding those for that price.
I've found several in the 45-48 range for lt depending what they have. They just raised trade incentive from 2000 to 2500 for trading a duramax in. So that helps a bit, would make the 45 one 42500 like you said. I agree any ltz lmm they want 40+ for even with 100k on it. I can do without all the ltz stuff anyway. Lt with most things ltz has except leather and center console is way less.