Very nice Greebo! 
Question, are there any variations on the M18 schemes?
I haven't really researched the M18 but I have only ever seen photos of them in olive drab, like the default. Olive drab and black and olive drab with winter whitewash are the only other likely ETO schemes. I am pretty sure the British and USMC never used them so probably none of those interesting multi-colour schemes that they painted the 75mm Sherman. Maybe the French might have had some M18s, but if so they would still have been olive drab.
BTW a returning skinner PM'd me a couple of months back to say he was thinking of skinning an M18 in the future.