How to configure ob_tidyhandler dynamically?

The PHP tidy extension has a function ob_tidyhandler^Docs that works with PHP output buffering^Docs as a callback, e.g.:

ob_start('ob_tidyhandler');

I know that Tidy has a lot of configuration settings^Docs, however I am hitting a road block to setup default configuration options for that output buffer callback.

Most of Tidy's PHP function refer to a tidy document or object, however with the output buffering that one is not accessible.

There is a configuration setting tidy.default_config, however that is not change-able at runtime, so it is not very dynamic.

Does anybody know if configuring the callback dynamically is possible at all? I remember I wrote a callback my own, collected all output and repaired it with a call to tidy_repair_string^Docs which accepts configuration as an array. But I thought it would be nice to not need to do that and just pass the configuration along for the output buffer.