Sorry to see another problem......
But another issue is the seating. 3 Kids, 1 Dad + 1 pilot = 5 seats. Most light aircraft can only seat 4 people. It's not like a car, where you can squash one more in.
There are a few aircraft that will take more than 4, but not many that can, and still get into a 500mtr airfield.
Other issues, that you might not appreciate given that you are a non flyer:
What would the mothers attitude be towards safety? Flying in a single engined aircraft is more risky than road travel, and significantly more risky than on the airlines.
Night flight in a single engined aircraft leaves very few options if the engine fails. Many pilots refuse to fly single engined aircraft at night.
Just some thoughts.
Might make more sense to by an appartment closer to your kids, and spend the weekends there.....at least the cost is going into an appreciating asset.
dp