forwen

You're most likely doing so already. But, please look into funding for whatever schools you're looking at. For every school that is unfunded in an area, there is almost always a funded one. Considering the type of environment you want to be in is another important factor to consider. Some people do well in a rural setting; others thrive in the city. Temperatures could also play an important factor. I think being happy is an important aspect to ensuring you finish with your best possible work no matter where you up deciding to apply.

Yup, I've already narrowed down the list of programs in Education as well as Linguistics departments, I was also curious if there would be similar programs in Rhet/comp programs but I haven't been finding many. So far, I've seen a few professors that have interests in multilingual writing in these kinds of departments, though some seem to be more focused on English-dominant contexts and L1 users of English rather than L2 writers. Thanks for your suggestions!

You should look into the University of Washington's "Language and Rhetoric" program, which might be a good fit because of its emphasis on linguistics as well as rhet/comp. They have a MATESOL program and a number of those faculty also teach PhD level courses. Plus, Bawarshi (genre scholar extraordinaire) is there, which aligns with your thesis project well. 
And yes, I think a Rhet/Comp PhD is definitely suitable for someone with your interests! There is a lot of demand for Rhet/Comp scholars with TESOL training and expertise in working with multilingual writers right now.

That's good! For some odd reason and for what it's worth, I've always had L2 associated with Arizona State University and Illinois State University.

https://english.clas.asu.edu/isearch-expertise/second-language-writing
https://english.illinoisstate.edu/graduate/phd_engStudies.aspx