[racket] Sandboxed evaluation with 2htdp/image requires

I'm having a problem with the error "cannot instantiate
`racket/gui/base' a second time in the same process" in a script that
I have to perform automated testing of student BSL programs. My script
requires 2htdp/image for its own purposes and uses
make-module-evaluator to create an evaluator for a student program.
The problem is that if the student program also has a (require
2htdp/image), it attempts to instantiate racket/gui/base which is
problematic (http://docs.racket-lang.org/gui/Startup_Actions.html ).
Any suggestions for dealing with this?

Thanks,
nadeem