The plastic would be OK as it is Polypropylene, just like in the commercial boilers, but they are a bit small.
Think about it. You are trying to end up with 23 litres of wort after the boil. Hot wort expands, taking up more room than cool wort. It also bubbles and foams, so you need a bit of head space. Hops also take up space and you have to start with more wort anyway because a one hour boil causes quite a bit of it to evaporate.