i was thinking along the lines of getting the last 2 peoples death certificate and seeing if the address on there and going from there. or if there was another way of doing this.
I think that would be a very good way to tackle this.
The death certificates should also tell you who registered the deaths, and where they lived, and it's always possible that the informants are still living.
Why not book a day in the Scotland's People Centre in the Mitchell Library in Glasgow? You should be able to find lots more than just the last two death certificates in a day, and the staff will be able to help you with how to go about it. It would also be cheaper than ordering two certificates from SP.