Covers on inside lighting

I have same trailer, what owners manual:)  As you look at lens it has plastic tabs, squeeze then hard together (difficult), at wide end of lens.  The tabs will push in and lens will come down.  There is a knack to it.  It takes some pressure.  I was surprised how much pressure it took.  If you have plastic detail tools, you can use one of those (like a plastic flat screwdriver) to assist.  Be careful not to break tab.  3-5 tabs on each lens.

I'd be worried about several things with heating them, most especially warping or discoloring them. I have a 2016 so I bet they're the same. I spread my fingers and grab the whole cover. While squeezing in, I turn the cover to get the notches into their slots. Once you get one down and get a look at it, it will become clear. Maybe start with an out of the way one to alleviate the anxiety about breaking. This is a little helpful

I found that putting a piece of masking tape on the plastic to serve as a pull tab works just fine. Pushing up on the plastic lens or squeezing it makes removal more difficult. The tape serves to rotate the lens without distorting it.