Level 3 writing advice- do I need a tutor/class?

I've passed the first two levels of the CFA on the first try- besides spending 300+ hours preparing, I think I'm fortunate enough to be good at taking tests (especially after going to what I would consider a pretty rigorous college) and teaching things to myself better than I learn them in a classroom, which obviously both fare well for something like the CFA.

However, I've always struggled to feel good about my writing. English is my first language and I think I am still a stronger-than-average writer but always feel a little shaky about writing compared to quantitative skills. So I'm wondering how best to prepare for Level III and hoping someone may feel similar and have some advice.

I don't necessarily want to spend time I that could spend studying/teaching concepts to myself, in a classroom going over topics I've already had the discipline to review and understand. But, I'm wondering if it would be worth it to find some sort of class or tutor that would focus specifically on how best to take the writing portion of the exam and maybe even read/grade my answers, since I think self-grading written answers is highly subjective and biased.

I'm in NYC so I don't think finding something along these lines would be too difficult but I'd love to hear your advice! Thanks