Hi Greg,
Yes, a 7782 outdoor AP is certainly capable of covering a few backyards.
Reducing your individual 2.4 and 5G Tx_power to 1/8th will reduce the range
and should still provide adequate coverage for your family. Elevating your AP,
perhaps to rooftop level, is good for performance, and can assure you of not
being w/in 2 feet?