The first problem I ran into was the xpack user bug (https://www.elastic.co/guide/en/kibana/current/release-notes-6.5.0.html#known-issues-6.5.0). Thought that would have been fixed by 6.5.2.
After deleting the indices and creating the hack user kibana is back up. But of course I lost all the configuration (should have realized this was going to be the case).
So first step is to recreate the index patterns. But just clicking thru "Index Patterns" in management resulted in the "Payload content length greater than maximum allowed" error. So I tripled the value to 3145728 and still get the error.
I'm starting to think I have some other problems.