No, I don't think it would hold at all. Serve the green beans--they hold their color
as well as anything else. And if you roast them, I don't find they turn gray--but they also won't hold.
And I agree about no briami--THAT is a lot work and hard to portion really because of the variety of things in it--and I LOVE it.
Green beans, tiny lima beans (we call them butter beans), even peas and carrots. Bring to a boil from frozen and serve.
Another green bean that is really good is Italan green beans. They are VERY good frozen, and I like them better than regular "string" beans.
Just my opinion, but serving that many, and having to arrange the oven situation, I think simplifying without compromising flavor is a good idea. You can get a LOT of green beans/etc. in a stock pot on top of the stove--spill them into a serving pan for serving.