Have you checked your insurance, as anyone in the forces is pretty much a no go. My mates in the marines are complaining that no one will even consider them for car insurance, and RAF is similar (lots of base time is the reason they give). So I'd go checking with them first before deciding on cars. Sorry to be a downer, but rather this than getting the car and finding your insurance is either astronomical or unnobtainable.
TBH, I would consider the 5 door, purely from the safety aspect, god forbid there is a crash, and your injured (or worse!), I personally would want to know my daughter (IF I had one
), was capable of being removed to safety via the rear doors quickly.
Tom