Great start, nice to see you researched it here then just did it. Congrats on that.
Maybe you saw this idea on here and it wasn't for you, maybe you didn't see it so I'll through it out there; if you have a modem jack on that laptop and know that you will never use it, clip the wires going to the modem jack close to the jack and connect those power wires to it inside the laptop. Then when you install in the vehicle all you have to do is plug in a phone line connector. It's a very neat way to do it and a very clean way to remove & re-install the laptop in the vehicle.
I will follow your progress and BTW, very smart not trying to put a timeline on the project, they usually surprise you anyway with the number of hours eaten up!