Yes, I know it's Chinese, but this seems like it would be a handy tool for setting camber on ifs and probably figure a way to use it for caster on a straight/I-beam axle? https://www.gearbest.com/car-gadgets/pp_009653263051.html??&lkid=16022646&fbclid=IwAR3JOxdqKSrfybnYQH6jabMEMjw-taubluPXP6xmr3CDNwdblsSU4fU7qOs
I'd have to see how it does caster... that short level on the end? It would be good to get you in the ball park after doing some work on the car.
I've bought other stuff from that company, r/c boats, drones, and I think a soldering iron. It takes a while for the stuff to come in, maybe 5-6 weeks, but they do have a pretty good reputation with the drone & R/C people. I don't have any ties to them, just thought that was an interesting looking tool
I think the short level on the end is to make sure the tool is level crossways so the camber scale is at its most accurate. He said caster on an 'I' beam. That is just finding a finding a flat,true surface on the king pin boss. If you were careful about getting it vertical you could use a magnetic base angle finder to do the same thing.