A bike trailer already folds flat and pops its wheels off for car trunk storage, that same design makes it one of the easiest items on this list to move.
Pro tip: Take the wheels off just like you would for car trunk storage, this is the fastest way to shrink a bike trailer's footprint for a move.
Watch out: The safety flag is thin fiberglass and bends or snaps easily if crushed under other cargo, pack it flat and protected on its own.