That looked like about 3 cords of firewood worth of red oak to me. In Canada its cold enough you could burn that in one winter no? Anyway, on the stump issue. That friend with the track hoe could knock over two or three trees and then you could pick away, and then the farmer would have no stumps? If not feasible, then you will have to come to some agreement with the farmer about stump height. I prefer to leave stump waist high if making firewood, as the rest just makes boomerang shaped pieces of different lengths which don't stack well. He might be concerned about cattle tripping on knee high stumps and breaking legs, so I would try and convince him to leave them chest or shoulder high so they could use them to rub on, rather than trying to get chain in the dirt.