How do these look for a bucket liner? https://www.amazon.com/dp/B003U6FMOK/ref=twister_B0040Q4XLW?_encoding=UTF8&th=1
Siphon out your beer and leave the trub behind. Either pour off some to collect yeast first or just seal it and throw it away. According to the Q&A they are food safe.
The only problems I see is the bucket lid might not seal but they don’t don’t sometimes anyway or the lid rips the bag and it leaks in the trash. You would only really need to sanitize the lid.