is a few arc seconds asking too much?
I have looked at tilt sensors and accelerometers, GPS modules and compasses. I am a little confused about whether I should use a tilt sensor to measure the latitude setting of the unit - related to the GPS position, or an accelerometer.
Why not just use an equatorial mount and just one motor?
Like all the best geek projects, I expect you would spend more time creating an automated setup than you would ever have spent doing it manually. That's not a reason not to do it, of course.