Your Search Area and Feature Area cannot be 1 pixel in size and certainly they can’t be of the same value – you’re way off here.
Track as per normal – with appropriate tracking options which include Search and Feature settings/size.
What you want should not dictate what you track. Rather, what you track should allow you to obtain what you want – sense make?
When you Apply the tracking data, you have the option to apply either X only, Y only OR X&Y tracking data. In your case, apply the X-only or X tracking data.
HTH
RoRKa
Intensive mocha & AE Training in Singapore and Other Dangerous Locations
Imagineer Systems (mocha) Certified Instructor
& Adobe After Effects CS6 ACE