CTL with hydraulic bush hog will do 5"-6" soft wood. there are better hammer flails made for chipping major wood, but not that you can just rent (as a home owner). I would call your local equipment rental guys (United Rental, Sunbelt, Kubota, ect) and see if they rent the CTL with the bush mower. they will likely rent the skid steer at one price, and the mower will be basically another piece of equipment to rent (if they have them). no idea how heavy/thick we are talking about, but you will be doing good to do more that 1 acre per day, working all day. Another option is a big old tractor with a HEAVY disk and heavy bush hog. if it's 75% less than 3-4".