Maybe a persistent log table is OK, and each transaction is responsible for deleting its own rows from it? Sounds like a lot of churn though...
Partitioned persistent log tables wouldn't reduce the total total amount of churn, but they'd distribute it into smaller chunks which autovacuum threads (or cron jobs) could attack in parallel.
That would, of course, increase schema complexity and there would need to be reasonable "static" partition columns in the parent tables.
