Might have a good idea on dealing with interest in moving vehicles

Quick background: As some of you may know from past posts, we live in a pretty rural area, the closest "street" is the highway (YIKES!!!). The main place we have to walk Caeda, if we want a decent walk, is beside the highway (there's about 20m between the trees and the highway, so lots of room). She shows more interest than I would like in the passing vehicles, especially if they are going slow (to turn off the highway) or are closer than about 10m. She'll stare and occasionally pull toward them a tiny bit. It worries me that in the wrong frame of mind, or if a vehicle was making an odd sound she might want to bolt at it.

So, here's my idea. TOUCH! Teach her to touch my hand every time a vehicle comes near, I'm thinking its the perfect counter to the potential bolting, it brings her closer to me if there is a vehicle nearby but we don't have to stop walking (I'd thought about teaching sit, but I could see that getting annoying if there's a lot of traffic!). Are there any reasons this would backfire on me? For those who live in more urban areas, how annoying would that be? I mean, who knows, I might end up moving somewhere more populated eventually.

My other main question about this is what is the best way to teach it. Should I make a point of taking her out to the highway every day for a week or so and just standing with her and getting her to "touch" for vehicles? How damaging/prolonging would it be if we did walks that were training sessions for this, and some walks where we don't practice it (basically walk for the exercise, and just keep an eye and strong hand on the leash)? I know both my DH and I might be prone to do this. Would it be better to just teach it in the front yard for the first while when the neighbour comes and goes?

Anyway, any thoughts or input on this idea? I can't believe it took me this long to think of it, but now that I have I'm wondering about shortfalls/tips that anybody might be able to tell me.