i don''t believe sailing in 50 knot winds is the way to go. if you have sustained winds of 50 knots i believe you would be much better off throwing out a drogue and going below for a nap. in those winds and the 30-40 foot seas associated with those winds you suffer too much of a chance of pitch poleing down one of the waves.
i believe a storm jib and trysail or deep third reef would work to about 45 knots but most storm jibs are very hard if not impossible to tack. You also get very tired very quickly trying to sail up and down the waves. it gets close to impossible to do on a moonless night.
if you really must have a storm jib i believe the jib should be no more than 5% of the height of the foretriangle squared and maximum luff of 65 % of the height of the foretriangle. the top of the sail should be distress orange . you also need to set up some very strong tracks forward for a correct lead.