Well, odd, no responses, eh?
Anyway, I tried model aircraft ball joints but there was no space to operate them, so then I came up with a great lightbulb moment. A slotted disc with a pin sticking up from the tiller, allowing the swing and rock of the tiller as it goes from one extreme to another on such an angled rudder stock. It worked, but I fancied some lack of precision would be difficult to build out, so, I finally made a pulley system, with a 1" brass pulley on the rudder shaft, operated by 2 1/2" PTFE pulleys on stainless shafts, held in brass housings epoxied to the rear bulkhead. The low profile Hitec servo that had sat in front of the GWS sail winch was moved to the aft compartment and mounted so it lined up with the 2 smaller pulleys. When my new braid arrives, I'll give a try. Then it'll be time to fix the after half of the deck finally.
You can see that, being a tight wad, I used J cloth from the Poundshop with the epoxy, to act as a strengthener as GRP cloth was pricey plus postage. Worked a treat and we're still using the rest of the sheets as dishcloths and sanitisers in this mad lurgi- ridden world. The model is made using sawn planks from a chair my Granddad made in the 30s from real Honduras mahogany. He was a top cabinet maker AND a model boat fan so would approve. The chairs never suited the table (which my daughter still uses) and then central heating caused the old hide glue to fail in the joints which then broke, so this was a good use for the beautiful wood.