Update..... In the end I gave up on getting the touchscreens to work. Instead I opted for a different route. Instead of using touchscreens for my passengers, I use mini keyboards with built in track pads. They are much easier and comfortable for the passengers to use, since they do not have to reach for the screens. All are wireless, so no wires. It looks like a blackberry, but instead of a screen, its a track pad. Very accurate and responds well. Its like these things were made for the MK802 and SS808. The driver still uses a touchscreen, but I am using a tablet that came with a screen.
So in short, if you want to use the MK802 and SS808, use a mini keyboard/track pad if being used for rear passengers. If you want to use this for main PC, try a capacitive USB screen. Resistive will most likely never work as far as USB is concerned. I would have tried a capacitive to see if it works, but I am happy with my iPazzPort Mini Keyboards. Gets rid of a lot of fuss with the screen.