Eliza,
 
I've never tried this myself, but I imagine, as long as there was other
stuff surrounding it, that the cage would be okay.  What I would do is
wedge it in real tight with the other stuff and maybe even put padding
around it (or towels, blankets, etc).
 
Hope that helps!
 
~Becky and Heather and the magnificent Seven: Abby, Andre, Annie, Arthur,
Avery, Bob and Peanut!
[Posted in FML issue 4046]