Yes, for most photos I try to have the centre of camera's lens at around eye level or a little lower (as if one were kneeling down to take photo or sitting in their car). This helps model photo look more realistic as it is the way we are used to looking at the real trucks. It also helps blend edge of model pavement surface into natural background.
Photos taken looking down at model may require larger surface to display model on or closer-in point of view. It's worth giving a try, some interesting results should be possible.
Forgot to post this earlier, one other "oops" I made when taking the Monfort W900 photos was the very first one, had white balance on camera set to "Tungsten" for indoor photos. Taking outdoor shot with this setting resulted in overall bluish cast and a "cold" feel, not the effect I was looking for originally but one that can give a moonlit or evening appearance to picture.
Setup for today's progress photos of the 378 Pete project was a little more "low tech", with it being a bright day out I could get away without a tripod. Surface is a piece of plywood about 4' x 3' which was filled one side, sanded smooth & spray painted flat black. By sitting it on top of my vehicle and blocking one end I was able to have just sky showing in background. (Snow & ice on vehicle roof protected paint, otherwise place a towel or similar cushion between plywood & roof). Camera was set on plywood, even with aperture of f/40 shutter speed was still 1/80 sec.