Last resort you could go to a gun range and ask to use their facilities there.
Do not go to a Gun Range with an Airsoft! These remarks are not directed at the OP he's squared away av'd and has a plan. these remarks are pointed at anyone else reading this thread that may have a similar position.
For simply zeroing and test firing it go to a game event or indoor field if you do not have a suitable private space available to you.
pulling out an Airsoft AK74 or similarly insane Airsoft Rifle or Pistol at a Fire Arms Facility will draw a lot of negative attention