Raise door, or install low profile A/C? Freelander 19CB

Thanks for the advice, Teachers Pet! But an 8" reduction in my floor would be a pond! I am on the coastal plain at about 7' elevation. My house is raised but the barn is at grade. first rain and it would flood. I am very close now I think...

Oh and no sweat on the header. It would be sandwiched on the backside with a 2 by 12...