We always used a spring loaded device with a sharp stylus to scribe a line on the centerline of the tire tread for toe measurements. It's a lot easier to see if you make a wide stripe on the tread with a piece of soft chalk first. The trick would be to find a shop willing to fabricate the specialty equipment needed to do axle bending- - - -something they might only get asked to do a few times a year. It's all done by "cold bending"- - - -no torch work involved at all! You're more likely to find people familiar with axle bending around a heavy truck (18 wheeler) shop, where straight axles are usually what's used on road tractors.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!