Rear wheel alignment

[Fazerider]

I’ve never had difficulty doing it by eye on any of my bikes.
Sight down the edges of the front tyre and adjust the steering until you see equal widths of rear tyre.
Gently prop a couple of straight lengths of 2 x 4 against either side of the front and recheck it’s still pointing at the centre of the rear tyre.
Now sight along the two sides of the rear, if it’s out of alignment it’ll be very obvious.
If you need to adjust do so and repeat the lining-up procedure each time. When it’s right just make a note of how far to offset the rear wheel from the factory alignment markings and you shouldn’t need to bother again.