What gives with the water cooling? I've done it for years on my desktop but it is just not needed on the Epia platform. Stick with the stock heatsink and fan, and it will keep your warranty in tack. If there is a bad combination it would have to be computers, cars, and water.
As for the display, yeah the video isn't going to make you happy if the monitors are cheap. However, if your current screens do not get any interference from the car electrical then your a step ahead. Most of the problems with RCA video is it is just blurry for small text. If you use large phonts then it won't be an issue. Even GPS can work good if you get a map program with resizable fonts. I've found that text size of 14 and above is readable (14 is barely readable).
Also one note is the Epia M series does support wide screen resolutions. I believe it's something like 848x412 or something like that. It does work and looks pretty good so give that a shot before you go with non widescreen resolutions. I've noticed that screens look a whole lot better when they are displaying in their native mode versus something Windows is trying to cram down their throats.