We also recently bought a ct13 and replaced the lights
with fixtures from an rv dealer that have the plug for bunk lights
on the sides we plan to line the back of the bunk lights
with velcro so they can be placed anywhere on the roof carpet they were only about $10 each but the bunk lights were a bit more they are 12v and we plan to replace the standard bulbs with leds. I ripped out the 30 year old nasty stinking carpet and installed allure flooring and couldnt be happier, i did have to put down a subfloor to level things with the fiberglass that bends out from the storage areas and epoxyed molding since you cant really nail into the fg. While we were at it we installed an outside light
also about$10, very handy when stepping out for a nature call in the middle of the night.