A. You can do a .htaccess rewrite /i/(.*) to /image/$1
B. You can add a route override (app/routes/overrides/route.i.php) and do a mapRoute (check the example in route.index.php for explore routing)
I need to change the css on the /i/ version. My idea was to copy the existing image.php, changing the name, to i.php, upload to directory /i/ and redirect /i/ to i.php.