You can also estimate the size of the vehicle. based on how fast it it going and the time between front and back wheel you could calculate the distance between the wheels.
with two strips you can get a lot more data than if you just have one. count, direction, speed, size, and times the road is active. I dont know if they active measure all that but its possible.
I agree wholeheartedly, I would also like to do it without worrying about cops