For students who have been out of school for a while, schools tend to care less about academic performance and more about life experience. It sounds like you've done a lot of work in the years since high school that will boost your application, which is great, especially if it's part of your "spike." If you're able to show a spike in something that's not strictly academic, that can still have a positive effect on your application - after all, students who show spikes in things like the clarinet or figure skating don't necessarily apply those talents in school.
I'd recommend reading our article on what students with low GPAs but high SAT scores can do, even though it doesn't strictly apply to your situation. There are some useful tips in the article about how to compensate for a lack of academic prowess in your application (although in your case, it sounds as if the issue is more lack of academic extracurriculars, rather than lack of good mainstream academics).