Hi Sophie!
I am a senior in the RC and took 3 semesters of RC Spanish! Over those 3 semesters, I also completed Bio171, Bio172, Bio 173, Chem 210, and Chem 211, so hopefully I can shed some light on what that semester might look like for you! I do want to preface this post by saying that I do not know how grading works for non-RC students taking RC languages. I reached out to my advisor and will let you know when I get an answer back!
That being said, in my experience RC languages courses are a lot of work, but I found them to be worth it. Because the classes meet more frequently (usually 8 times a week), there is daily homework. This is very different from the structure of other college courses and it does take up a lot of time. That being said, homework assignments were never extremely difficult and I felt as though the frequency of the class helped a lot with my language proficiency compared to my friends taking LSA Spanish. This may be beneficial if you are interested in taking upper level French courses as you mentioned. I also found that upper level literature Spanish courses are easier, so it was nice to have the 4 semesters of language requirement out of the way as I began to take harder pre-med classes.
As far as GPA, RC students are required to take their RC language courses pass/fail. Because of this, the class has a large focus on practical language skills and professors are less nit-picky about specific grammar structures, etc. This made my semester a lot less stressful. I looked on the LSA/RC websites for you, and it looks like non-RC students have to take this course for a grade, but I cannot find a definitive answer so I would reach out to your advisor. If you do have to take it for a grade, I would not worry too much about this class contributing too much to your semester GPA. Your grade is based on many different factors and I was able to get As on most assignments! 
As far as your overall schedule, I took RC Spanish II (the equivalent of RCLANG 290) while taking Bio 172, Bio 173 and a 3-credit seminar. In total, I was taking 16 credits. I would not recommend taking more than 16 with RC French, especially because this will equate to a lot of in-class time each week. I would recommend postponing Bio 173 until later because it has significant out-of-lab work. I would recommend pushing another class back as well, either SOC or ALA. Chem 210 and RC French are both going to require a lot of work, so I would recommend taking only one additional easier course. 
I hope this gave you a better perspective of the RC language courses and taking them in conjunction with Chem 210/211. Please let me know if you have any follow-up questions!
 
Best of Luck 🙂
Isabel

Hi Sophie! I just heard back from the academic director at the RC. He confirmed with me that RCLANG 290 (French Intensive 2) is mandatory pass/fail for all students and that it will fulfill LSA language requirement even as a non-RC student. For me, taking a class P/F was a great opportunity to focus on improving my practical skills without the pressure of grading. It was also nice to be able to focus on my pre-med req grades, especially for Chem 210! If you have any additional questions about taking a language P/F as a pre-med student, please let us know!  Isabel