Backpack with boots inside, not tied dangling on the outside. There are many threads discussing some or the extra" nice" things to bring along that are authorized,but not on the packing list. Wear your low quarters. Everything you need can and should fit in the backpack.
SOC tactical backpack is authorized as well as an awesome choice. DS uses his for the academic year and flight travel. Don't buy a cheaper replica that looks nearly identical, have heard bad things about them.
You don't want to have to carry anything on RDay