The problems with following this red herring of the Electra towing an abandoned lifeboat of the island go beyond the simple fact that an aircraft like the Electra didn't have any engineered capacity to tow anything.
The one available photo of a lifeboat on the island shows it to be well ashore in sand and light vegetation. That means it was carried there either by a storm assisted tide or a very high tide. It also means that the lifeboat which is a very heavy clinker built wooden boat had been exposed for about eight years, after the Norwich City was wrecked, to the weather and resting on sand. That would have dried out its caulking, which in those days was basically a hemp and tar mix. Also it is likely that the timber would have rotted where it was in contact with the ground. It would have needed to be recaulked before it would be sea-worthy.
Given that it is highly unlikely to the point of being impossible that EA and FN had the means to make the boat seaworthy that is one impediment. The next is that the boat was far too heavy for a single person to drag anywhere, even if in the very unlikely circumstances the caulking was still good. Even if it had been considered EA and FN would have not have been strong enough together to overturn the boat to inspect the hull then right it again. Now we get to the idea of the Electra dragging the boat from the shore to the ocean.
The place where it is hypothesized that the Electra landed is a narrow strip of fairly level reef on the water's edge distant from the actual shore and separated from land by the inner reef area which is much rougher and crevassed coral. Also the proposed level landing area is at 90 degrees to the shore. The Electra would even if it could be coaxed into moving could not get a straight pull. But far more important is that as I explained that there is nowhere to attach this hypothetical rope, and by the way there is no indication that EA and FN had a couple of hundred yards of rope on board or available to them on the island.
What will happen if this imaginary rope is attached to either the tail wheel or the main undercarriage, which are the only available strong points, is that if power is applied the rope will straighten out and as the shore is higher than the edge of the coral reef, and the lifeboat is both impeded by friction with the ground and its quite considerable weight, this will lift the tail of the aircraft up either by raising the tail wheel, or because the thrust of the propellors will tug the aircraft against the rope and cause it to rotate around the axles of the main undercarriage which also raise the tail. Once this happens the aircraft will start to tilt nose down and that will cause the propellor blades to hit either the water or the coral. They will then be bent out of balance, stalling or destroying the engines. So the aircraft will then be rendered immobile and the lifeboat, if it was seaworthy would not have moved one inch.
Put simply the aircraft would be written off very quickly. I suspect that EA and FN if they had even had a spare couple of hundred yards of rope would have worked that out very quickly. Aircraft don't make very good tractors.