"I bet this is a lot harder...." ? Not at all - just means once you get your string (I use very fine black sewing thread) set up parallel to the back wheel, the measurements to the front wheel rim are a bit shorter than those to the rear wheel rim. It's a bit more complex with IRS -- you have to know the track difference between the front and rear. You measure to the center of the rear hub, and then must add/subtract the half the difference in track to set the distance to center of the front hub. That gives you a parallel string to measure front AND rear toes against.

Forces acting on the front tire as the car rolls down the road tend to force a car to go toe-out. The faster you're moving, the higher the forces are. And the softer the front suspension bushes are, the easier it is for the front wheels to be forced into more of a toe-out condition. Typically, it takes a bit of static toe-in for the car to achieve a bit of toe-out when cruising down the road

I'm running much stiffer than stock poly bushes in the control arms, and no rubber at all in the coil-over struts, so I don't get a whole lot of rolling toe-out. When I aligned it last, I set toe at 1mm-2mm toe-in each side. And that seems to work great. Perfectly stable at cruise. No 'dartiness' at all.

Setting it at zero was just to allow a low speed test drive. I did it with front end of the car about 6" in the air, supported under the control arms - so the suspension isn't perfectly at ride height. If all is well with no leaks/noises, I'll restring it and set it back at 1mm-2mm toe-in with all 4 tires on the ground.

BTW, you can make your own swivel plates to go under the tires to allow adjustment of toe. 12"x12" VCT floor tiles from Home Depot (about 75 cents a piece) with a bit of table salt sprinkled between then. They're only 1/8" thick - put 2 or 3 under the front wheels with salt sprinkled between them. The salt crystals act like little ball bearings and allow you to adjust toe without trying to overcome the friction of the tire on the garage floor. They're also great for leveling up the car when you're setting caster/camber or doing corner weighting.