No extender needed for 285-65r18 (32.5” tall).
I think the wiper-blade and bumper clearance will be a combination of tire width and wheel offset.
These wheels are +25 offset (so the tires are pushed out 16.5mm vs stock +41.5mm offset).
The photo doesn’t show it, but the tire is around 25mm (1”) away from the bumper and wiper blade.

 

Thanks! I just put it on this a.m. and everything you said was what I experienced. The increased offset countered the extra width perfectly. One more Q for you: I was hoping to reuse the Land Rover center wheel badges, but they seem slightly too small. Did you get those center dark caps from Evo Corse or somewhere else?

 

^^^
I used the center caps that came with the wheels.

 

Thanks for pioneering this, @aao4473 . Here's my experience: Link