Laying in the undercut is not that big of a deal. A trees balance stability is not that affected by that unless the backside is rotten. It takes alot to bring a big tree down. I once worked on a clearcut that had 3 different gen's of tree sizes/ages. 4' diameter, 8' diameter and 25' diameter. We climbed up the stump 15' to get to the top and there it was 25' in diameter. Awesome but sad as well. The BC coast a hundred yrs ago was covered in trees like that. Their all but gone today. Those were great forests and we were fools to chop it all down.
b
bill