Admin - Load existing admin template as a submenu page

Question

I'm trying to save my client a few clicks. I've created a custom role of "Customer" and I'd like to get them to that screen, without having to have them click "Users" and then select the "Customer" role.

So, I have a custom menu called "Orders". I'd like to add a submenu called "Customers" and "load" this page:

users.php?role=custom

I'm guessing I have to use the callback function on add_submenu_page and then load that template? What's the right way to go about this?