Whisker Pole response
My yacht is similar in design to yours. Our main spinnaker is fairly large and the pole extends well beyond the fore-stay so we end-for-end the pole. Up to twenty knots this is fairly easy. Above that it can get difficult. We use a second set of sheets but that's another story. It is essential that everyone knows their job!
The skipper has to to keep the boat flat and almost sail by the lee. At this angle the spinnaker is set so both the brace (sheet through spinnaker pole beak) and the sheet are the about the same length. The cockpit man has to ready to release the downhaul. We let the uphaul take the weight of the pole during the gybe. On our boat the pole is set up with both the uphaul and downhaul attached to a ring. Each ring is attached to the pole by two lengths of wire about a metre from each end of the pole, so when pressure is put on say the uphaul the pole and the two pieces of wire make an isosceles triangle (two wire lengths equal). This is necessary if you end-for-end your spinnaker pole. If you dip gybe you can attach the downhaul close to the end of the spinnaker pole but this removes the option of end-for-end gybe in light winds which I think is a better option once you have practiced it.
The mast-man should be able to disconnect the pole from the mast and the spinnaker should stay full (as you are running dead square down wind). The mast-man now pulls the cord releasing the pole from the spinnaker sheet. If the beak points down, this makes the mast-mans job even harder as he has to lift the pole to release the sheet. With the beak pointed up, The sheet is released as soon as the cord to the beak is pulled. The mast-man (maybe with the help of someone else) attaches the end that was on the mast to the old spinnaker sheet while the old sheet end (the really hard part in a blow) is now attached to the mast. Fortunately we have a BIG Morie from NZ. We say he pulls the mast to the pole not the pole to the mast. We then gybe the main. Up till now the main has provided a small wind shadow making the difficult task of reattaching the pole to the mast just a little easier.
With a dip-gybe, if the pole is too long, try raising it well up the traveller on the mast. If you are only after an inch or so this will allow you to dip gybe.
By the way, we have what we call a Whisker Pole. It is about 2 metres long. On a shy run, our whisker pole is attached near the base of the mast at approximately a right angle to fore and aft by sheets leading for and aft and attached to small horn cleats on the deck. It extends beyond the gunwhale by a foot or so. With the brace running through the Whisker Pole the brace is keep well away from the stauchons, preventing them from bending. Does the skipper get shitty when the whisker pole is not used on a shy run. You bet he does. No matter how hard you try you can never get the stauchon straight again.
Hope this is of some use to you.