you may or may not be as accuret as a alinment shop but if you think about how and what your doing to measure you will be within 1/16" -1/8". your not going to feel pull by off 1/8" (front to back) and if it's off by an obvious amount 1/2" or more which you are going to see right now, youll know this is most likely where the problem is or its been hit . . . point is its a cheep place to start.
profesional aliments are not as accuret as you think. I can do toe in toe out with a long adjustable rod and be within .025" which will change at the very next pot hole you hit.