Hi Ross, I have been looking at these M10 thread stainless lifting eyes. They have a SWL of 230kg each which I think should be plenty when the eight of the hovercraft is spread around 4 of them. I would use a plate on the back face possibly with an M10 bolt either side securing the plate (with the eye bolted in the middle) to spread the load. I don’t think your solution will work for me as I don’t have a 30mm lip around the hovercraft deck, it’s probably more like 15mm I reckon.
The eyelet has an internal diameter of 25mm - do you think this diameter will work with the shackles on the crane to lift it into the river?