In 2013 my wife side swiped a metal pole coming out of a filling station. Damaged the two part hinge system for the basements doors. I was able to get the pieces that fit to the door from Monaco but they did not have the piece that attached to the side of the motorhome.
I was able to get it from Visone RV, https://rvparts.visonerv.com/
They cut off a ~7' piece from the side of a motorhome, I live close enough that I went and picked up.
So you may contact them and see if they can help. I'd suggest replacing a longer piece. The cured portion above and below your picture are separate pieces, I'd go to that joint.