I use the fastrax caster/camber gauge for doing the alignments on my cars. I have a magnetic gauge too but it doesn’t work on my Duster with the aluminum hubs and wheels :D. I have a set of turn plates I also found second hand, super helpful. Although some greased plates works fine too, you just don’t want anything binding up. I measure the toe using a set of longacre toe plates. There’s no way I would try to set the toe off the fastrax gauge, it doesn’t hold to the rim with enough force to pull an accurate, repeatable measurement. Plus you’d need two, and I only bought one. Toe plates were cheaper than buying a second gauge
Longacre Toe-In Plates 79501
As for the toe, yes, it does change with tire height. Well, assuming you’re not using toe plates like I am, in which case the toe plates are always the same size. But the difference is pretty small. Degrees is more accurate for sure, but so are the digital racks the alignment shops use to get the toe in degrees. And it’s not a huge difference. For example, if you change the tire height from 25 to 26” with 1/8” total toe in, the total change in degrees is for both wheels is only .009. If you change the total toe from .125” to .120” with a 26” tall wheel, the total change is .011. I can’t measure to .005” with a tape measure, so, you know why the factory didn’t worry about changing the toe setting for different tire heights.
You can play around with this calculator to see what I mean. Degrees is more accurate, but you can’t measure that accurately with a tape anyway.
Convert Toe Inches to Degrees