You always want to manually clear the area you will be cutting so you don't hit hidden objects that can damage the mower, tractor, you or others.
You may want to look into getting a grapple for the loader. It will cost a little, but I think it would really help.
You should have had the crew that select cut my grandpa's place. They chipped and hauled off all the tops and limbs. I am sure they were sold to add to the logger's profits. It really looked nice when they were done.
There are several threads on here about grapples if you search.