Spatial Indexing can only go on for as far as say a double float can go. If the random seed value is set using the x,y,z coords of where you are in space then the scenery can be randomised from that. I suppose that could be very big (I was just imagining it then).
It's pretty much similar to the galaxies generated in Elite. I've a few ideas in mind to expand on it.
You would only really need to place the scenery as defined by the surround areas using the seed value (ie density of stars, galaxies and debris).
It would be interesting to see how you get on with this iSilver.
Warning! May contain Nuts!