Personally, I'd refrain from building a wine rack into a vehicle simply due to heat. Heat will kill your wine! I think that's the most important thing to keep in mind.
When we travel with wine, we either put them in coolers with ice packs (keeps heat AND light out), or if we're camping and don't want to bring bottles, we bought a few Platypus pouches and will fill them with and get all the air out. They're resealable, too.
Also, an electric fridge is also a great way to keep your wine at a cool, constant temperature.