This order-total module will allow you to charge a Rural Surcharge for shipping to remote areas, based on the first 2 characters of the postal code.

Easy to install. Just upload the files maintaining the directory structure and then go into Admin and install it.

admin > modules > order_total > {install}

After installing the module configure it to your liking.

While this has been tested on a new build of 1.0.8.20 and PHP 8, if you do spot anything odd please PM me.