Is 1/2" leaf spring relocation worth the trouble?
That will likely require lots of fender modifications. That wheel has 5.5” of “front space”, which is approximately 2” more than what fits in the fenders without cutting anything. It will definitely hit the front edge of the fender and depending on how much caster you run, it will contact the splash guard on the backside of the fender.
That’s not entirely accurate. If it’s 18x10” then it is 11” wide outside to outside. If it has a 6” backspace that’s outside of the lip to wheel mounting surface. So the front space is 5”, not 5.5”.
It’s also not 2” further out than what fits inside the fender without modifications. My 18x9’s are +35, so, 6.3” backspace. But my brakes kick them out an extra 5mm per side compared to a 73+ disk kit. So, 6.18” backspace to compare to OE disks. That means effectively 3.82” of front space, so those 18x10’s are only 1.18” further out than my 18x9’s if they’re mounted on OE 73+ disks.
I was running those wheels with Duster fenders without rolling the lips and pushing the fenders, at a slightly higher ride height than I am now. Granted, that was all the room there was so I don’t disagree that you’d need fender work to run those 18x10’s, you absolutely would. But the numbers you gave aren’t quite right either, it’s not as bad as it sounds.
And there are guys that have run 18x10’s up front, with various amounts of fender modifications. Personally I’d want a little bit more than 6” of backspace, a couple tenths makes a big difference when you’re fitting them that tight.
With my current fender modifications- extended fender to bumper brace, lips rolled and roller used to push the fender lip out, I’m pretty sure I could get 18x10’s on it at my current ride height, which is pretty low. I’d still be stuck running 275/35/18’s on them until I raise my inner fender, because I already just barely touch the tires to the inner fender at full suspension compression. So if I wanted to run say, 285/35/18’s I’d either have to raise the car or raise the inner fender. But my tubular LCA’s allow for more compression travel than factory LCA’s.