depends on the size of your tunnel, miniture trees won't get soo big - plus, they don't grow so fast that you couldn't get a pair of lopers to them!!
there is a thread on here about using windbreaks - think there is some good netting that can be put up to provide suitable wind cover, and if you plant some willow, that'll grow fast enough to be woven together to create a wind break
have a hunt for the thread on growing trees on an exposed site