Yes, Steve is right. I forgot to mention what he brought up. You don't have anything to go off of since you don't know what it should be. You can, however, make an educated guess from making some measurements, math, and flight testing. Anyway, setting up the bottom of the fuselage as zero may or may not be true zero. If you don't know this, you really can't get anything more than relative measurements between the wing and stab, but not take true measurements. The aerodynamics book will be of great help. If I wasn't an aviation major in college (and an aerodynamics junkie), I'd really be up a creek trying to figure it out.

Don't listen to everything at the field. There are a lot of old "veterans" that spout BS 60% of the time they open their mouth.