Haven't seen one of those since my dad bought an second-hand 80's Chevy pick-up that was 'customized' by one of those van conversion companies. It had bucket captains chairs, a console and overhead panel made of what looked like pine, tires that stuck out from the fenders and a two-tone faded paint job.
Pretty sure no one makes one to fit the RL, I'd measure the width at the top of the 'A' pillars and search for a suitable on the internet. JC Whitney or eBay may be your best bet, or maybe you can find an old one intended for a different truck that happens to be the right width.
If you find one and install it, be sure to post the details and some photos.