Argentra, restraining it has the mouse already fighting before it's even been hit by your snake - which I would think would be far more dangerous for your snake. When I drop live prey in the enclosure, it's clueless of impending danger. I'm feeding ball pythons from 200 grams all the way up to 3000 grams. They're all very efficient and swift hunters. The smallest ball I've ever had was 70 grams, eating live hoppers - no problems.

Elvyra, place newpaper down on top of the substrate. And even then, a small piece of aspen isn't going to hurt your snake - they ingest leaves and twigs in the wild, and their stomach acids are designed to digest fur, hair and bones - a little substrate won't be an issue.