For real! Babies are so portable. They do require a lot of stops for feedings and diaper changes though, so there can be no hurry! But if you are in a camper and have two drivers you wouldn't need to stop...i've been thinking about getting a bus and ya know converting it into a lil home or heck even getting a nice big volkswagen or something. i have a 4.5 month old too, and i doubt he's gonna be needing much space for a while.
Our toddler is a little more restless, but still does well in the car. We drove from Michigan to visit my mom in Florida last year and she did pretty well. I think that 18mos is a sweet spot, also. And bringing along the laptop for movies was indispensable.