I have used my CC-400 series in the field too, albeit not to far from the car, mostly inside a 1-mile. I just bought a Toyo 45A (that should arrive next week, yea). I don't know if my range from the car will change much but the new camera will fit in the wife's Miata, the old one won't.
Mono-rail cameras do have certain advantages with regard to movements, setup, and rigidity. even their cases are handy. In my Eurovan the CC-400 case provides a nice catch all for all the "necessary" bits we all seem to drag around; filters, film holders, dark bag, ...
Typically as I get out of the car the camera gets locked onto the tripod head ready to use and carried from there as a unit so weight isn't really a difference. In this mode physical size isn't much different either.