Tonneau covers are great, Ben. I have a white one for my blue Capri and a black one for the White XR2.
I used to have a '66 TR4A IRS with a tonneau. It's great when it gets cold to put on your stocking cap, leather jacket and gloves, then put the top down with the tonneau and crank the heat up underneath the cover.
Convertible top cruising in mid 30-degree weather (fahrenheit, of course) - sort of like a 4-wheel motorcycle.
MIDCO Mustang Capri may still have some black ones left, but he also buys them from other owners and may get his hands on a white one from time to time. You should check it out.