I'm not really qualified to offer much help here but I will put my 2 cents in. Laser is a pretty good way to go and with some creative engineering almost anything can be made to work. In the farming world, GPS and auto steer is as common as an old shoe. Something we have to deal with is GPS signal drift which can vary widely from one day to the next and one end of the field to another. To remedy the problem we have a fixed ground network enabling RTK. With RTK/GPS we are spot on from one day to the next and season after season. The short story is your signal and accuracy will vary throughout the day and change significantly overnight without RTK. To the question: Almost all of the guys installing field tile around here use laser exclusively. One pretty creative tile guy rigged a laser receiver with a wireless "cab cam" focused on it so he could easily see what the laser receiver is reading.