With minor work and the removal of Special:MobileEditor this seems possible.
I started a proof of concept patch to demonstrate: https://gerrit.wikimedia.org/r/267199
{F3289539}
[x] Remove the hook that redirects all action=edit's to Special:MobileEditor when wgMFAllowNonJavaScriptEditing=true
[x] Add editor ResourceLoader module skins.minerva.fallbackeditor to pages with action=edit
[x] Style anon warning box with warningbox class (might require change in core)
[x] lead edit icon should be visible https://gerrit.wikimedia.org/r/347126
[x] Reduce size of the license text and warning messages making more space for the editing form https://gerrit.wikimedia.org/r/347127
[x] Decrease size of text area so for logged in users without an anon warning box the buttons below it are visible on a standard mobile screen.
[x] Update MobileFormatter to output action=edit in the URLs of edit links
[x] skins.minerva.editor should hijack edit links
[x] Edit icon should be styled to the right without non-js as it is in JS preferably with icon, but be careful with how many icons are pulled down
[x] cancelLink, mw-editButtons-pipe-separator and editHelp should be hidden in mobile view - they look cramped.
[x] Discussion link should not show on editor
[x] Page actions - edit and watch should not show on editor
[x] Enable wgMFAllowNonJavaScriptEditing=true on the beta cluster to allow testing
[x] Verify non-JS editing works on beta cluster
Test run:
Obviously whether or not you enable it is also a decision that might result in more spam, so you'll need to think about that :-)
[] Enable `wgMFAllowNonJavaScriptEditing=true` on production and investigate impact on editing
[] Remove `wgMFAllowNonJavaScriptEditing` and allow editing without JavaScript by default based on good results
Post-removal of `wgMFAllowNonJavaScriptEditing`:
[] Remove Special:MobileEditor