I say no supports, but you might want to support the ladder some to reduce bending.
Print in Place Gate & Arch: https://www.printables.com/model/436334-medieval-palisade-gate-arch-print-in-place-no-supp
Matching Wall Set: https://www.printables.com/model/435566-medieval-palisade-wall-set
& some Spiked Barriers: https://www.printables.com/model/435558-medieval-palisade-spiked-barrier