did you follow that link? psychos2 builds boxes to fit in the spare tire area, read that thread, there is pricing and ordering info

as for video/headunits search for the pioneer AVIC-N2, someone here did a very nice install with that unit

i like the setup i have for video, i have my dvdplayer/source unit in the lower din slot and a standalone flip out monitor in the upper din slot, my source unit plays DVDs plus has an extra video input for video games/computer (or gps in your case) and my monitor has two inputs as well, one from the source unit and one from a rear view camera, just make sure the monitor you select has the capability to reverse an image in case the camera you get doesnt do it automatically