I liked your idea of using the Colour restorer on the darker patches. I have had quite a bit of success today. I used a few coats of Netrol stripper, then the colour restorer. The advantage of this is that you get no dust everywhere in the boat from sanding, which I think is a major plus.
I think I will proceed with this first, then resort to sanding only if I have to. It also means the same approach can be taken for veneer and wood surfaces.