@noah-cochran The Girl Who Could See by Kara Swanson is a first person present tense book alternating with first person past tense. It made sense, but I think it could easily have gone south. If you’re careful I think you could make it work. It would be easy to forget what tense/person you’re writing in. I’d suggest you try doing a short story or set of short stories, or even a few chapters before committing to a whole novel alternating between persons and tenses. Also, decide before hand whether it will be the same intimacy with both of them. First person is usually limited, (although I just finished a first person limited omniscient)
I have written first person present tense for short stories. If you think it would be helpful, I would gladly share some with you.
Quoth the raven, "Nevermore!"