There was also a Grumman Tracker there, it had two controls that crossed the joint. I assume that one was for aileron, but I have no idea what the second one would be for. View attachment 791097
Aileron trim on the Tracker would seem to be electrically controlled, so no control cables, only wires. As per the flight manual below, the only control cables into the outboard wings would be the ailerons, with the spoilers mechanically linked to the aileron movement. Flight manuals are less detailed than maintenance manuals, but the spoilers are probably linked to the ailerons via cables and pullies.
I've not really heard that the radiator was a big issue in ditching. The worst thing about the Hurricane ditching I've read about many times is the fact that it sank like a stone.
Integral air bags within the fuselage should address that. IIRC this was a common feature on carrier aircraft.
As for making a better Sea Hurricane. Keep it simple, put on the best Merlin available, ensure the radio and beacon navigation systems are top notch. Increase the fuel load or add drop tanks. Other than that, as long as the RN's carriers have Implacable-class wide lifts to accommodate the non-folding wings, the main improvement for the Sea Hurricane is quantity.