Found a 4.5" 4:3 TFT LCD screen that takes composite.

[Soop]

http://cgi.ebay.co.uk/ws/eBayISAPI.dll? ... K:MEWAX:IT" onclick="window.open(this.href);return false;

Pretty good eh? Only problem might be thickness (although that bezel looks pretty deep), and the 12v.

But I think that's as good as it gets.