You don't need a PhD to go into academic medicine or work in administration. Hell, you don't even need a PhD to run an MD/PhD program...You'd be taking a risk by applying MD/PhD because 1. You are putting yourself among a much more competitive pool of applicants (higher risk of not getting in anywhere) and 2. Your reasons for wanting the PhD are flimsy at best. It is not a ticket to respect, power, and professional advancement if you hate the idea of doing the thing it trains you to do. People that get to those positions get there because of excellence in research, medicine, and teaching, not because they have PhDs.
There are plenty of MDs who have succeeded in your goals.
There are plenty of MD/PhDs who have not.