I grew some in my high tunnel aquaponics system during my first year, back when I ran it cooler. After the first year I converted it to accommodate tilapia breeding, which happens best a little over 80F, so I can't grow greens well in there anymore. I still grow a lot of buttercrunch lettuce in there during the winter when it's slightly cooler, but it's not as good as it would be if grown at the proper temps, so I mainly do it just to feed the fish. (I toss 3-5 big heads in there each day and they annihilate them.)

I haven't tried growing Romaine lettuce in my semi-pit tunnel greenhouse yet, but now that you bring it up, I think I'll do that next winter. During the winter it's perfect for growing cool weather crops. Spinach and buttercrunch lettuce do extremely well in there, so I think Romaine will too.