If you want the OEM porch light you might need to call Thor for a part number and then try contacting their out of warrantee retailer to see if you can get it that way. If you don’t mind not having the OEM version you could try Command Electronics:
The Lights — Command Electronics
Failing that, there are RV wreckers that might be able to supply you.
https://www.rvbasics.com/techtips/rv...ent-parts.html
Good luck.