To tag briefly onto the solid advice above: as an undergrad, I double majored in English and philosophy. I found it to be a powerful interdisciplinary cocktail, and I completed my BA feeling prepared for graduate studies in either field. I should clarify, though, that I was on the literature end as opposed to rhet/comp. On that front, I can only speak anecdotally.
Speaking to graduate students in both departments, it was quite common to hear that they transferred across these disciplines between their undergrad and grad programs. This is especially the case for students in the MA programs. It really does come down to clarifying how your studies in philosophy tighten your grasp on the theoretical underpinnings officiating dialogues in literary-critical research. This is not a particularly hard shift to justify in a SOP. I would consider finding an English professor (at best, two English professors) willing to contribute letters, if at all possible. If you composed philosophy-heavy papers in any English classes, even better! Those professors may be able to attest to your strength in both fields.
I am continuing into an English PhD program after my BA, and used two letters from English professors, and one from the chair of the Philosophy Department. Adcoms want to get a snapshot of your unique approach to academic work, and an interdisciplinary background is nothing to be too concerned about...in many cases, it just might make you a memorable candidate. The only caveat is this: if your undergraduate philosophy curriculum fell heavily on the side of analytic or continental philosophy, the way you connect your background in philosophy to your continuing studies in English may vary.
I, too, would be willing to talk to you about my own experiences. I also encourage having a pass over the rhet/comp thread, if you have not done so already. Best luck moving forward! It is an exciting time.