Widetrack rear arch extension clips
 

Simply put, are there clips available for the rear arch extensions that apparently always break upon removal?

Nope

https://i100.photobucket.com/albums/...h/DSC_0420.jpg

Afraid not yeh they do break when removing, ive just replaced mine too freshen the car up and tried my best to remove the old ones without breaking them but they all did .

They are part of the plastic mould unfortunately so if they break... they break, you can bond the arch trim back on with tigerseal etc but it will be 99% impossible to take off after so if you go this route don't plan on removing them again.