If it was me, I'd get hold of a 6 or 7 ft long piece of 1.5in Stainless tubing, or even a composite tube such as an old windsurfer mast.
Hinge one end near the bottom of the transom (on the inside of the boat) and have a fastening the 'mast' clips into near the top of the transom. Even a bolt and big wingnut would do.
A ribraider type antenna could be mounted to the top of this 'mast'.
When not in use it could be folded into the boat, and raised when needed.
The dangerous(to You) antenna would be several feet above your head and behind you when you were sat at the jockey seat.
RIBBED For extra pleasure.
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