Not sure what this contraption would look like but the JC pump isn't really meant for 'on the fly' dripping.
I hate to sound sanctimonious about the dangers of distracted driving (we all hate "Nanny" finger wagging around here---particularly when it comes from the government or rabid anti smokers). But frankly, some of the comments from folks who seem quite sure they can pull off topping/dripping/dipping while driving scare the crap out of me.
It's plain foolish--and selfish--for any of us to insist that driving while fussing with
juice and a PV is a perfectly acceptable practice. If you manage to get
through one or ten or a hundred car trips without placing yourself or others in danger, it will only encourage you to keep taking the risk. All it takes is one split second with your eyes off the road.
I'll add the
Wetbox to the list of safer alternatives suggested by others. It's a simple and effective box mod with a squeeze bottle juice-feeding system. (It uses cartos but I put a T-tip on the end because the carto mouthpiece can get hot and uncomfortable.) I put one in my breast pocket whenever I need to use the car. I'm familiar enough with the device that I know how to turn it on and use it without ever needing to look at it. Even so, I feel like I need to be careful. If the Wetbox isn't working properly or the battery is running low, I put it down until I can give it my full attention.
The other alternative I use in the car is
swedish snus.
You have lots of safer options. I hope you'll find one that suits you.