Older toddler won't stay out of exersaucer

Any ideas on how i can toddler-proof it without needing two hands to prep it for putting the baby in?

Saying 'no' is treated as a game, as are punishments, time outs, having things taken away, etc. We've re-furnished most of the house to cut down on the climbing and such, but i'm stuck on this. She just climbs up and over baby gates so gating it off won't work.

She loves her baby sister-practically smothers her. So i can't put the baby down unless it's in bed behind a closed door and i can't get anything done like this