To be honest, you don't sound like you'd be a very good MD to me.
I don't think you can MD/PhD in clinical psych. Very few, if any, of the courses will be similar. I know it's +4 years to your med school if you MD/PhD in neuroscience but that's the closest you get if you want to get your PhD while doing your MD.
As for people asking the point of this, a licensed psychologist with a PhD/PsyD can administer alot of forms of analysis that cannot be done by somebody who just has an MA, MEd or MD. If you're interested to know the fine line between the professions, read on.
The difference in their approaches -
The reason people usually don't MD/PhD in psych is because at that level of study, they're simply different jobs. At the master's level, they're different approaches (therapy vs. meds as people like to generalize). However, at the doctoral level, psychology will teach you forms of psychoanalysis and interpretation of it. This is usually not directly relevant to the management of psychoactive medication. It's the psychologist's job to help make that information relevant to the medication and therapy (often meaning simplifying it to something a psychiatrist could work with). As a psychiatrist, you'd give a therapeutic approach, then prescribe or modify medication. It may sound like the psychiatrist here is ignorant of much information, but they really aren't. They're simply trying to fix the problem, rather than identify it. For problems strongly linked to a medical condition or problems with simple psychology behind them, a psychiatrist is ideal--sometimes even better than a psychologist--to analyze the situation. The professions often work hand in hand, but they are by no means the same thing. If you do a MD/PhD in psych, you'd be acting as the psychologist and the psychiatrist in the situation. You'd be handling less patients given the fact that you'd most likely take time to analyze and give therapy, then consider prescription. You'd make much less money (if that's an issue) because you'd be overqualified and trying to work three fields of practise (analysis, counseling, psychiatry) and unfortunately, two of them pay much less than psychiatry alone.
