RE: Could he have flown any lower?
I have been buzzed by a P51 a half a dozen times over the years. The last time he was at 20 ft above my head; he was low. The lowest I have seen was a guy at the airport with an RV4 with retracts did a low pass at the same hight as if his wheels were touching; it looked more like a model than a real plane he was so low. Prop no more than 2 ft above the ground.