Here's a render at where the map is currently, I've ended up taking the approach of making a small version of it, and getting the terrain levels and heights done, as that way I can see what height chunk goes where. I made it this way because halfway through I found that I paid almost no attention to accurate height levels when planning out the map, so some sections had to be merged/changed as I went (the mountain/volcano area to be specific had a lot of issues to be resolved).

Regarding scale difference, the ring in the centre is the current Hub model, scaled down by 0.001, so this new world map is nice and HUGE, with lot's of ground to fly about in, although I'm not looking forward to trying to model the roads/props at this scale, so maybe once I get the terrain smoothed, I'll bump up the scale a tad?

Thinking ahead, the next stage in this process will be smoothing out the height differences and forming ramps here and there, then placing in the main roads, once that's done this new world will be technically playable, so I'll upload a new build once that's done.