On 2009-09-02, mm wrote:

I can install this from inside the attic, without borrowing a ladder,
but it requires at least a ring of T1-11 between the box and the
fixture. At least a half inch smaller than that the box or fixture
base is big. Would that be okay?

No. 2008 NEC section 314.20 says "In walls and ceilings constructed
of wood or other combustible surface material, boxes, plaster rings,
extension rings, or listed extenders shall be flush with the finished
surface or project therefrom."

Cheers, Wayne