Finally, there are some real costs that the rental companies are passing on: Airports charge high rents to tenants like car rental agencies, so the cost of maintaining a special area for refueling is somewhat higher than it is for a typical highway gas station.
If you had CV-22 type technology, could have been done with a single in-and-out pass -- albeit with helicopter refueling with C-130 type assets -- moving directly into the objective area, and then being able to extract during that, again, single period of darkness.