Eric devised a way to cut a hole in the bottom without the entire basket falling apart, and then we used a piece of thick upholstery foam to fit snuggly around her waist so the basket wouldn't slide down. It worked great. She was able to walk, use her hands and move easily up and down stairs.
She got lots of compliments and everyone seemed to like her trick-or-treat candy bag: a Meow Mix cat food bag.
I think if Bea had her way, she'd dress up as a cat every year.