Leaves on Romanesco and Mauve Caluliflowers

Hi All
I've sucessfully grown some Romanesco and mauve cauliflowers this year.
I've got them under a (large) mesh cage in a raised bed surrounded by leeks - however, the leaves have grown so well that they are trying to burst out of the cage!
The cauliflowers themselves are a large fist size, so still have some growing to do.
Is it safe to cut back a few of the larger outer leaves (making sure that the inner caulis are protected from the sun)? I want to get the leaves away from touching the sides of the cage - which I can't make any bigger.
I've had some cabbage whites flying around, and they keep trying to land on the leaves which touch the mesh. So far, they don't appear to have laid any eggs as they fly off as soon as they land on the mesh, but I'm scared that one will manage to! I don't want the crop decimated by caterpillars.
As a side note - I also planted the same plants in another bed next to courgette plants and spinach - and they are about 1/10th of the size of the ones planted uniquely with leeks!