I'd say rethink this. Yes failure is absolutely a possibility you have to contemplate if you are trying to go into one of the hardest fields to get into, coming from the starting point of a much older age and no college background. Most folks will not get plastics, derm, rad onc, the most competitive specialties. If one of those is what your ultimate dream is, then step back and look at medicine as a whole and see if you are really on a good path. You absolutely need to go into this NOT WITH A SPECIALTY AS YOUR DREAM, but with BEING A DOCTOR AS YOUR DREAM. If you dream of being a physician, then that's great, you are not too old and with hard work you can attain this. If you dream of being in a very very very competitive subset of physician as your dream, not so great. Even with the hardest of work, you may not be able to attain this. Most people who want plastics don't get it. Most won't even make it to the point where that is a possibility on the decision tree (based on grades, board scores, evals). I'm not saying this to be a downer, or to say that it's impossible for you. I'm just saying that you don't want to go down this road with this being the thing that would make you happy. You have to be happy with the road itself. Look at it like playing sports. You play, eg, basketball because you enjoy playing, not because you want to be an NBA star. If you are only doing it to be an NBA star, but don't particularly enjoy the game, I'd say find something else. So too with medicine and subspecialties. If you enjoy the "game" of being a physician, go for it. If you are only doing it to get to an end point most won't get, this is a really really foolish path to start down.
Cool it with the whole "failure is not an option" talk. That's fine if you are a 19 year old premed, but a nontrad in his 30s with a family, you have to be more of a realist. Yes, failure is an option -- in fact it is the likelihood coming from your starting point, if you deem not getting to plastics as a failure. Deal with it. If you shoot for the stars, you usually don't get past the moon. So even better would be to have the attitude that you'll be shooting for the moon, and if once you get there, the stars are an option, then fantastic. Such is the path here -- you have a lot of years to go to become a doctor -- and you can get there if you are really devoted, work hard, and have family stay supportive. But once you start telling us your dream is to be a plastic surgeon, then no, we can't give you the same kind of assurances that you can get there. And so again, if that's where you need to end up to satisfy this dream, it may not pay to uproot your life and start down this path. If, however, that is but one of many interests in medicine, and you'd be similarly happy becoming an internist or a physiatrist or FP, then I'd say sounds good, proceed. Sorry to be blunt, but the problem with SDN is sometimes that there are often many people to cheer you on and too few who tell you what you don't want to hear.