Great little project, right up my street! You're making a good amount of progress in a short time as well!

I would have started with a simplistic full-width half-max of the profile, but Gaussian fitting is probably better and more noise tolerant (but as you say, more complex!).

I assume you're summing the image across the horizontal. r.e. rolling shutter, might be helpful to perform some frame averaging?

Out of interest, whats the cost of the laser? I can see it replacing a DTI and precision straight edge, and being very useful for performing the measurements in the same plane.