Rotten Wood from Wing Walls

[D Man]

The wood on my 2017 Thor Fourwinds Wing walls behind driver and passenger doors are rotted out about 10 inches from bottom
What thickness is this wood so I can replace I can not get a answer from anyone except to piece it together and silicone Any help would be appreciated
I’m fixing it myself

 

[mhbell]

The wood on my 2017 Thor Fourwinds Wing walls behind driver and passenger doors are rotted out about 10 inches from bottom
What thickness is this wood so I can replace I can not get a answer from anyone except to piece it together and silicone Any help would be appreciated
I’m fixing it myself

Some pictures of the area would help.
Mel