Bondo filler has even hotter solvents than squadron putty.
I would think you could use Squadron white or Testors Contour putty, but test them to see if they would melt it.
I think this would be a great application for Elmer's Fill-nFinish as it it water based and has zero possibility of melting the plastic. Yes, I have recommended a non-solvent product.

__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL, if you have to ask what is "NORMAL" , you probably aren't !
Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !