I am sure it is possible to measure caster with an angle finder. The problem is finding a spot to measure it. If you had a front end with kingpins it would be easier. You are basicly measuring the angle of a line drawn through the centerpoints of your upper and lower balljoints viewed from the side of the car. If the ball joints make a perfectly verticle line, you have zero caster. If your lower ball joint is more forward, you have positive caster, if more rearward you have negative caster. Speaking of road crown, yes in certain countries the left side will need more positive caster
And certainly local climate will have an effect on how much crown the roads will have. Where I live, roads have a lot of crown.
