There are some self-paced online programs, such as BYU Online, that could allow you to churn out two years of foreign language before you graduate, although it might not be the most inspiring experience. (Or you could enroll quickly and drill down on a first-year language this summer, in order to take a second-year language at school in the fall.)
Another option could be to consider the merits of a gap year abroad, i.e. with AFS. Of course this would be a huge commitment if the only reason is to check a requirement box, but it could be a great experience for other reasons too, and a lot of overseas high schools offer high-level STEM classes that you might not have taken yet, so that you could keep moving forward in those areas as well. Even if you’re not sure you’d prefer this option, you could keep it on the table and see how things turn out with your college apps.
Looking at the College Transitions list of “Foreign Language Requirements for Colleges” (I’d post the link but CC will block it - you can Google it), there are a number of strong STEM schools that don’t have a FL requirement or a strong recommendation. I’ll leave it to you to verify on the individual websites, but according to this list, check out Caltech, RPI, U of Rochester, and Stevens.
A lot of public U’s, and some private ones, will accept CLEP credit so that’s an option too, as suggested above.