Handling a bad puppy during a sit?

Hi guys! I’ve been sitting with Rover a few months and pet sitting in general for a couple years. I’ve always owned dogs and was never a stranger to bad behavior but this sit I’m on currently is a demon. She’s a puppy (3/4 months) and the owners have her crated most of the day. I come in early in the AM before I go to my job, a walker comes in around lunch, and I come back straight after work from 4-8:30. So from 6-12,12:30-4, and 8:30pm-5:30AM she’s crated. When I come in the afternoon no amount of play tires her out but she’s very mouthy and has drawn blood biting me while blatantly ignoring the toy I offer for play. This biting and mean behavior goes on the ENTIRE evening I’m there and I’m at my wits end. I’ve tried trading for toys, letting out a loud OW! To let her know that wasn’t acceptable, stood up and ignored her (she bites hard on my ankles in this case), rewarded with training treats nice play behavior instead she either savagely bites me or tries to chew the couch. Nothing works to the point i almost cancelled the sit because I work a full day with horses and to accommodate these owners I’m getting up at 4am to drive to their home to take care of her, working all day, driving back from work straight to her (no shower no dinner nada) then repeat and I’m just so frustrated and I’ve raised Huskies