If you already have an idea of the angle and placement of the head as it will be merged into the terrain you could perhaps do that thing I've read /seen a couple of others do and that is to render the desired view(s) of the head in Poser, take it into Photoshop or similar, make a greyscale image of that and then use it in Vue as an image map to model a terrain with. Easy to apply your ecosystem on then as the head etc will all be terrain with this method. Never tried this myself (on my 'to do' list ) but I've seen where someone did a cowboy terrain figure for instance that looked amazing .

" Try and be nice to people, avoid eating fat, read a good book every now and then, get some walking in, and try and live together in peace and harmony with people of all creeds and nations."
-Monty Python