Autosave with TinyMCE
I have made some progress on this. I downloaded the TinyAutoSave module from https://code.google.com/p/tinyautosave/ which I believe is more recent than the 'autosave' plugin included with TinyMCE 3.4.4. There may be updates in the latest version of tinymce, but I haven't checked. It seems the codebases have forked, however.

Anyways, I ended up removing autosave from the tinymce.inc file located in sites/all/libraries/wysiwyg/editors. I put tinyautosave/ into sites/all/libraries/tinymce/jscripts/tiny_mce/plugins.

The solution involved was to not use the 'restoredraft' setting, and use the 'tinyautosave' one instead. I have some strange way that builds the wysiwyg settings table but it basically does:

$settings['tinyautosave'] = array('tinyautosave' =&gt; 1);