I've thought about this many times as there is a ravine down the road down from me with tons (20+ cords, I am sure) of fallen EAB-killed ash on county property. So far I haven't attempted to retrieve any of it because I've been able to score easier stuff, but the day will come at some point. All of the possibilities seem difficult and time-consuming. I think my best bet will just simply be to buck and carry/roll each round up one-by-one. If there is a slope involved, it's going to be tough no matter what.