How do you bath a wiggly almost toddler??

My baby girl, 11 months old, can stand up, but not valence very well. I adore bath time but I short of me getting in the tub with her, I can’t get her in a secure position. Since birth shed had a baby bath tub but not she just keeps stepping out. We also have one of these,

But she still keeps getting up. It wouldn’t be so bad but she can only stand for a few seconds before she falls over.

I’ve tried just letting her sit straight in the big tub but she keeps slipping and sliding around. She’s hit her head a few times and if I hadn’t been right there she would have gone underwater.

I think once her balance gets better it won’t be a big issue but atm I’m at a lost. Tonight I used a bumbo and it was ok but not ideal.

I need ideas y’all.