if you read [Solved] Problems with api submissions error on submissions page - #4 by ctgraham
you will see that @ctgraham uses directives at an Apache virtualhost level to simplify the task. Even Apache document said so ( .htaccess files at the expense of some additional complexity.) Apache mod_rewrite Introduction - Apache HTTP Server Version 2.4
I will give you working example for virtual host RewriteRules if you want? Sorry but I will not be able to help with .htaccess RewriteRules.