OP - Its doable, just not pleasant.
I am taking Biochem/Microbio/Genetics/Ecology-Stats all at once, and it is SUPER hard to near impossible to keep up with this. I will never again take 4 heavy science classes at once. However, I work about 25 hours a week, so take this with a grain of salt. I guess it really comes down to if you work or not. Do you work?
I say, if you work, DONT DO IT. If you don't work, it is doable and can be manageble for at least 1 quarter/semester. If you try this for a full year, you might burn yourself out. Also, the only reason I would consider such a class load is so that you could graduate on time. If this is not a concern, I see no reason to do it.
Also, I think O-chem would definitely help with biochem, but is in no way needed to do well (at my school at least).
good luck 👍