306 rear arch liner - missing

[Danez 6 1 Cars]

My 5 door phase one 306 has the classic missing nearside arch liner. The inner wing is showing surface rust so I need to sort it asap. 

 

Problem is they're a bastard to find so if anyone has one or knows of one please let me know.

 

Failing that I was thinking I could get rid of the rust back to metal, primer it and then apply waxoyl? Has anyone done this? I'm guessing it'd be a good substitute for the arch liner if not a bit awkward to apply. But I have a compressor with a paint gun so that should reach fine. 

 

Or is there any better methods for sorting this from your experience? 

 

cheers