Great job recovering from the hack!

I know how hard it is to keep an SMF forum secure. I ran a much smaller forum on SMF, and it was a constant battle (both SMF 1 and 2). Eventually, I switched to something else that was easier (for me) to keep secure.

(I'm not suggesting changing to another forum package is the right thing to do here as it sounds like you have a really good understanding of SMF security vulnerabilities and how to mitigate attacks now, and that's really the most important thing).