Personally, I would sail the boat without the spi gear if you favour that in strong winds. I do that myself now and then for various reasons.

Spinnaker sailing in 20 knots is all about the state of the watersurface and being wel trained in the procedures. The latter you can only get sorted by doing alot of 1-up spi sailing in the 12-18 knots range. Each second you are able to execute the manouvre quicker leave less time for things to go wrong (gust hitting etc). Also "Boatspeed Is Everything" holds. When you slow down then things start hanging up or getting snagged. Practice, Practice, Practice.

The state of the watersurface is a given and you can't influence that. The more flat it is or the longer the wavelength the easier it all becomes.

When using a rope-ladder then use it near the hull. Otherwise you will swing only under the beam without getting up higher. If the ladder is lead down along the hull then the hull prevents this swinging and you can pull yourself up (while pushing off sideway agains the hull).

Other then that the best solution for high wind solo sailing is in my opinion T-foil rudders. I'm allowed to say that, but that is how I feel about it. A platform that is highly stabilized and have a much slowed down dive behaviour makes the boat alot more controllable.

Wouter