Have you thought about hooking up an automotive horn? I mean , it probably wouldn’t have helped the last time, but I have a lot of near misses with large trucks and SUVs that can’t see me. The stock horns on the Miatas are too soft. So I got myself a pair of Hellas Supertones for both of them

HELLA 003399801 Supertone 12V High Tone / Low Tone Twin Horn Kit with Red Protective Grill, 2 Horns https://a.co/d/5M2Hzyu