DV Info Net - miniature sets and HD

I have heard that makeup can be problematic when using HD digital--you have to be extra careful.
So in a similar vein, we are planning to shoot some ext night scenes indoors using a faked ground surface and some forced perspective. The location is desolate with ruined buildings in the BG. I used to do this on a smaller scale in film, but for this we want to have performers with miniatures off in the background(how far depends on the space we get). With a black backdrop for the night sky. The buildings would be obscured even though my modelling miniature skills are good. I wont be the camera person and havent used digital for this sort of thing. The camera is not determined yet but we are trying for a higher format(f-900 or SI-2k if the shooter who has it is available).

I know greenscreen is the norm--but I prefer miniatures and partial sets for this, and digitally paint-photoshop the background for static shots. I just want to avoid greenscreening around the performers directly as much as possible-especially when there is some rapid movements(motion blur).

Just wondering if anyone has tried something like this using HD digital formats and give me some pointers on what to consider.
Thanks