Here you can see what i did. Very ugly but simple and works. Just some square steel tube with some 8 mm nuts welded. Some poliurethane foam, faired and fiberglass. Dimensions were taken from photos of perth's adapters. Be carefull with the tail it's very fragile as there is little aluminium to hold everything. My tail is lost due to this. But a very good improvement.
Thanks for those, actually I was more interested in this part... "It will rust (I sail in freshwater) so I bought some solid carbon rods to replace the steel and give it a high end touch"
Are you able to share whether the rods worked and how you got threads in them (helicoils or a simple bolt and nut?). Reading about galvanic corrosion "www.corrosionpedia.com/galvanic-corrosion-of-metals-connected-to-carbon-fiber-reinforced-polymers/2/1556", apaprently "Aluminum alloys are extremely vulnerable when they are coupled to a carbon composite." but I don't know if it's any worse than steel, plus the Foils are carbon anyway!
Anyway, I am making (stainless) steel ones for now, struggling getting the holes drilled on the centreline and also @ 35c/c without a drill press.
Cheers
k.