IHMO, med school and clinical psych phd programs are very different, from the day-to-day life, the material, to what you will be doing after you graduate and licensed. Make sure you really consider what it is about med school that makes you want to go that route, not just as a backup or safe plan alternative to clinical psychology. You may find yourself miserable in med school. I've also heard that post-bacc programs tend to be very competitive because everyone is gunning for med school, unless you are in a program that guarantees entry.
Another thing is med school isn't short either. Assuming your post-bacc program is 2 years, and assuming you matriculate right after, that's 6 more years until you get your MD. If you do family medicine, I believe it's a 2 year residency. Anything other than that, including psychiatry, is at least 4 years. I'm not sure if pediatric psychiatry may be more on top of that. So you're really looking at a minimum of 8 years from today before you can practice, that is assuming that you get in on your first try. Will you may not have to move around as much as a medical doctor, it is overall going to take you the same amount of time or longer before you are a full-fledged doctor.