Silly me for not mentioning the balled up newspaper trick! But you say there is no room anyway in her enclosure.

Even in a rack I think you could darken her enclosure, either with a tinted tub like Becky mentioned, or just tape a towel or paper to the front of her tub (outside of it obviously with the tape).

When you say this one has been a problem eater for forever, does that mean while she was at the breeder too? In that case, I think I'd be a bit miffed the breeder didn't mention that. Maybe you could call and ask if they remember this particular snake and did they have any tricks that seemed to work with her?