Max Post Length: Different for Administrators

Although it is quite easy to use a plugin to override the max_post_length setting, it would be nice to have the option to edit the post length limit for certain users (e.g., administrators). I presently have a use case where administrators will need to make fairly lengthy posts (some around 300-500k characters cross-posted from WordPress), but no other users on the forum should ever need to post something that length.

Admins can temporarily relax the limit for themselves.