I used ABS plus-P430 just for the prototype. It starts softening around 240 Deg F. I'm contemplating between ULTEM 9085 or PPSF for the final material. They both have heat deflection above 320 Deg F. To be precise 333 Deg F for ULTEM and 372 Deg F for PPSF. So why not go for the PPSF, right? EXPENSIVE
Also, I have created slots instead of bolt holes to adjust the positioning of the license plate mount. Technically it can attach closer to back light or deep on the passenger foot pegs... Whatever makes you happy
Homework tonight: Design license plate LED mount. Perhaps a little covered section for the wiring.