I was not able to view your taillight pic. I searched for your model rv and see that your light is a square. That is an easy DIY fabrication.
I fabricated two different rear lights on my own by using a new light inside the OEM light. I drilled a new hole next to the old socket and ran the wires to it.
The second time, because it was a squared lens and easy to fabricate, I used a white plastic dollar store cutting board in place of the red lens. You might be able to screw it in place or as I did , glued it in place after installing an LED light onto the cutting board. If you shop for a large light the fabrication won't look too bad. It will look like white trim surrounding the new LED and blend into the rear of the rv. Just use a matching sealant on the seams to make it blend.