I've inherited a Poolmaster floating chair. It was being used by a guy of about 450 pounds and a woman of about 300. She fit in it and floated just fine. Him not so much.
The main float chamber was deflated and they left it for dead, but it's a puncture and not a seam rip. Easiest fix ever.
It's much more substantial than the Intex sit n float, but narrower in the seat. I fit in it less well than he did, and it's super unstable. It'll be better for 300 pound girl than it is for me. Shorts girl isn't going to fit, but I'm going to bring it and hopefully she'll try!