I've got a question for you - do you want to be a Marine? Or do you want to "experience" being enlisted in your road to being an Officer? The only reason I ask is that the Reserves are VERY active nowadays in the GWOT. My squadron was activated for 2 years, and we're on tap to be activated in the near future. If you want to be a Marine, and that matters more than anything else - than good luck and welcome aboard. You will find that your Officers will be more than willing to help you (provided you're not a shitbag). If you're doing it for the experience along the way, I'd be hesitant - if for no other reason than there are no guarantees and you could be screwing yourself down the road.
Don't get me wrong - I spent 2 1/2 years enlisted, KBay was prior enlisted, Crowbar was prior enlisted, but I'd be willing to bet none of us went into it looking towards being an officer. We just wanted to be Marines. None of us would swap our experience for anything, but it's going to be a longer more difficult road than you think. Especially when you want to do a LDS mission...
Oh, and if you are truly desperate to be a Marine Helicopter Pilot - don't let the jet fags dissuade you from that!