yes i would drive a mini excavator up that hill to plant 70 trees just keep the blade low so prevents the machine from tipping back, i dragged a 6500lb up a hill so steep the 3 ton mini excavator wouldn't drive up the hill with chipper chained to the bucket. i had to dig the blade about 5" into the ground with the arm as close to machine as it would go and then back up, and extend the arm while keeping the chipper from smashing the chute into the ground. it took me about an hour to get the chipper out of the area, i didn't even have the mini on the site, but luckily it was only about 4 miles away, so i was able to get it quick, i can load and tie down a mini in about 5 mins with chains and binders, front and rear, fastest on the east coast....
I do what other landscapers say is impossible or can't be done....but your operator should be fired. he clearly has little experience in the machine.
fully lic. and ins. 10yrs exp.