Amazon affiliate: SEO Help Needed

This is the pickle i'm in.

I have a keyword lets call it "hat world" which has about 2000 monthly searches

However "pink hat world", "green hat world" etc all have about 700 monthly searches.

Would I have to make separate reviews of each combination on my amazon site? My fear is I will end up repeating many things which may affect me SEO.

But I still want to rank for all combinations

All your help and past experiences will be much appreciated. Thanks