I was in a similar situation: I had to replace a panel in our bathroom on our Axis.
Since I didn't have to have it ready until this spring I had time to try different things. In the end I found a local cabinetry shop and gave them a sample:
The top item is the new panel, the bottom is the reference panel the cabinet place was trying to match. (In my instance the replacement panel goes on the backside of the reference panel.)
Now that I have it installed, you can hardly tell the difference between it and the rest of the RV.