Boom operators on the KC 135 are USAF active or reserve, not sure there are any Air National Guard units out there. No experience required. Each unit has a recruiting web site, office and contact information listed on line. Remember you can have different options available as you move forward…4 year degree, working towards a private and other ratings, trying to get on with a unit, etc.
Google a KC135 or any other unit (C130, C17, F16) in your home town or within a few hours. Go talk with a recruiter..ask questions about being a pilot or joining the unit as enlisted. Boom operator, Flight engineer..load master, crew chief all depends on the units needs. You can always say "no" at any time and most people fail to even walk in the door to talk with a unit to get smart on their options.