12-14 acres of boxblading? Ground covered with vegetation, too? You'll spend the rest of your life doing that with a little tractor and a boxblade. I'd go with TXDon's suggestion. Mow it down as much as possible, remove any bigger stumps that exist, then have someone with a BIG tractor and disc come in and break it open.
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They'll get the ground opened and rough levelled in a day; then you can do some touch-up work and maybe even overseed it with your eMax. If there are any really big holes/ruts that wouldn't get filled by discing, you might fill them with additional soil beforehand.
Google Image Result for https://www.deere.ca/common/media/images/product/tractors/row_crop_tractors/2011_7r_series/7280r/r4d010291_7280R_642x462.jpg
They'll get the ground opened and rough levelled in a day; then you can do some touch-up work and maybe even overseed it with your eMax. If there are any really big holes/ruts that wouldn't get filled by discing, you might fill them with additional soil beforehand.