thats a better answer than mine. but, if you want to move the whole assembly back, so it still functions the same, you cut out around everything to do with the light
like this
make a cardboard template to move it back 2" with ears on both sides
you can use 16 gage from a hardware store and bend it with a vise so the one side will attach to the core support, and the other side to the piece you cut out
eg.
if you have a welder, plug weld it in, if not, you could use sheet metal screws.
dont need too many tools for this, a vise, sheet metal cutters, some cardboard.
anyway, thats how i'm gonna do mine.