I suspect you could get the correct cover from J&R if you called them. Which one are you talking about? There is an inlet cover on the bottom half of my trailer that appears to be plastic and a metal outlet cover on the top half that's held on by 1000 screws. The top one is the louvered one on my trailer.
J&R can probably help with the trim strip too.
Hi-Lo 1707T - Tire Minder TPMS on Tow Vehicle and Trailer, 300W Solar Battery Charger, Equal-i-zer WDH
2014 F150 Platinum 4x4 3.5L EcoBoost SCrew