Hi lenny,
When I bought my VX there was a long list of things that needed doing. One was the fact that the LCD was not working having tried a number of car hifi dealers in the area who all wanted to charge me mega bucks or flog me a new unit these guys felt it was a challenge and managed to get Clarion in the U.K. interested in sorting it out which they did (it was sent back to Japan) so they would be able to tell you if you can put any other unit into it. At the rear left hand side is what I think is the camera junction box and I noticed a conector there which is either BNC or coax there may be some way of connecting this. Anyway I have posted dutchie who owns a Japanesse spec VX and is out in Japan at the moment asking if he can help.
Best regards
David Wiltshire