Michael, neat ideas, but don't forget to have a plan B for when the cable mechanism seizes (if Bowden type) or breaks. As you say, rust does not discriminate, and generally given time EVERY cable release meachnism will seize or fail in some way - inevitably with the relevant panel in the closed position. So you'll need some access route to release the catch in this event. On my X-type it involves removing the front undertray, jacking/ramps the car, then going up from underneath, through the engine, with a very meaty rod made up from socket set extensions, about 20 inches long, and using the weight of the rods to hit the seized lever. On my Reliant it involves removing one set of headlamps. I have no idea what the baby Fiat will need - maybe removable hinge pins? - but I'm sure you will come up with something.