There is an Italian company (or are they German? Can't figure it out) selling an 8.5 x 18" wheel that - they claim - is fully compatible with the Disco/LR4 brakes, without mods:
http://www.mudtech4x4.com/cerchi-raid/?lang=en
Kinda-sorta looks like the 10-spoke design of the 18" LR3 OEM wheels. I also like the fact they are 8.5" wide, should allow 285/60R18 tires to "sit" better over the rim than narrower 8" rims such as the Compos PD1881s. Price is not terrible compared to the Compos (mostly thanks to the strong US$ these days), although I have no idea how much they would charge for shipping a set of these from Europe. It'd be interesting to see if anyone has purchased a set yet, it would be nice to get another bolt-on, quality 18" aftermarket rim option for the LR4, other than the Compomotives.