If you already have a spinnaker pole you could use that;   the lengths are the same,  and a small loop of line (about 4 mm) permanently attached to the clew of the sail will enable the end fitting to attach to the sail.

If you don’t have a spinnaker pole,  the stresses on a jibstick are pobably somewhat lighter,  so you could make one out of wood.

I imagine that you don’t intend to use it in competitive racing,  so although Class Rules are a useful guide you need not be a slave to them.    Your choice of design;  length 6 feet.

Oliver