camphora and nova-anglica can probably be hardy to at least -10c as mature plants and in favorable (cold wind-protected spots). in myh experience nova-anglica can loose branches in high winds more than some other species but even in my windy area my biggest tree of this species is nearly 16m tall. rubida seems variable in hardiness and several trees have proved tender in my USDA 9 location. the closely related and very similar looking dalrmpleana has been more reliable. you might post on the "Hardy palms in temperate zones" website and ask for help from frank calia/"frank in Cincinnati" who has access to some very hardy seed selections of a number of eucalyptus species. tell him "George sent me", LOL. hope this helps.