I clipped all the large monsters off their sprues. I did this quickly and roughly, leaving a large nub of plastic. I want to be able to come back and finds all the bits I need to clean up, so I made no attempt to cut close to the model. Each monster was packed in a ziplock bag and they all went in one large kraft paper box.
Which leaves me with a lot of empty boxes!
It's not perfect, but the monsters will get assembled pretty quickly, I hope. In the meantime, this takes up much less space.