Quote from EarthLCD.com: "Can I use this LCD outside?
Not yet (o.k. maybe in the shade or car with tinted glass) but we are looking into backlight enhancement. This is available as an analog monitor as the EarthVue-12R."
I would email them and ask them more questions regarding the use of this particular LCD model in your vehicle. It has only Contrast Ratio 150:1 and Brightness 150 nits-- which is my opinion is not enought for daytime use.
But, these are very nice screens. They go for $250 on ebay.com