I have travelled a bit with my kilt and accessories. It almost always involved checked luggage for me. Jacket in a garment bag on a hanger, and kilt, sporran etc folded in the suitcase. Usually I fold the kilt in quarters as others have said.

The one time I hung the kilt in the garment bag it came off the hangers during the always careful and super gentle baggage handling process. When I got to the hotel it was in a ball in the bottom of the garment bag and was plenty wrinkled.

I might check out that Celtic Croft kilt hanger garnet bag for future travels.